diff --git a/src/component/contents/DraftEditorLeaf.react.js b/src/component/contents/DraftEditorLeaf.react.js
index 82eb2e5ef6..b1affbf9da 100644
--- a/src/component/contents/DraftEditorLeaf.react.js
+++ b/src/component/contents/DraftEditorLeaf.react.js
@@ -17,11 +17,11 @@ import type {DraftInlineStyle} from 'DraftInlineStyle';
 import type SelectionState from 'SelectionState';
 
 const DraftEditorTextNode = require('DraftEditorTextNode.react');
-var React = require('React');
-var ReactDOM = require('ReactDOM');
+const React = require('React');
+const ReactDOM = require('ReactDOM');
 
 const invariant = require('invariant');
-var setDraftEditorSelection = require('setDraftEditorSelection');
+const setDraftEditorSelection = require('setDraftEditorSelection');
 
 type Props = {
   // The block that contains this leaf.
diff --git a/src/component/handlers/composition/DraftEditorCompositionHandler.js b/src/component/handlers/composition/DraftEditorCompositionHandler.js
index 4790163045..de3f1cd8f1 100644
--- a/src/component/handlers/composition/DraftEditorCompositionHandler.js
+++ b/src/component/handlers/composition/DraftEditorCompositionHandler.js
@@ -45,7 +45,7 @@ let resolved = false;
 let stillComposing = false;
 let textInputData = '';
 
-var DraftEditorCompositionHandler = {
+const DraftEditorCompositionHandler = {
   onBeforeInput: function(editor: DraftEditor, e: SyntheticInputEvent<>): void {
     textInputData = (textInputData || '') + e.data;
   },
diff --git a/src/component/handlers/drag/DraftEditorDragHandler.js b/src/component/handlers/drag/DraftEditorDragHandler.js
index 4c3a7d9a6a..ee0aeaf0ff 100644
--- a/src/component/handlers/drag/DraftEditorDragHandler.js
+++ b/src/component/handlers/drag/DraftEditorDragHandler.js
@@ -39,7 +39,7 @@ function getSelectionForEvent(
    * found when Flow v0.68 was deployed. To see the error delete this comment
    * and run Flow. */
   if (typeof document.caretRangeFromPoint === 'function') {
-    var dropRange = document.caretRangeFromPoint(event.x, event.y);
+    const dropRange = document.caretRangeFromPoint(event.x, event.y);
     node = dropRange.startContainer;
     offset = dropRange.startOffset;
   } else if (event.rangeParent) {
@@ -62,7 +62,7 @@ function getSelectionForEvent(
   );
 }
 
-var DraftEditorDragHandler = {
+const DraftEditorDragHandler = {
   /**
    * Drag originating from input terminated.
    */
diff --git a/src/component/handlers/edit/commands/SecondaryClipboard.js b/src/component/handlers/edit/commands/SecondaryClipboard.js
index 828a61a9d8..2c89e4d641 100644
--- a/src/component/handlers/edit/commands/SecondaryClipboard.js
+++ b/src/component/handlers/edit/commands/SecondaryClipboard.js
@@ -15,27 +15,27 @@
 import type {BlockMap} from 'BlockMap';
 import type SelectionState from 'SelectionState';
 
-var DraftModifier = require('DraftModifier');
-var EditorState = require('EditorState');
+const DraftModifier = require('DraftModifier');
+const EditorState = require('EditorState');
 
-var getContentStateFragment = require('getContentStateFragment');
-var nullthrows = require('nullthrows');
+const getContentStateFragment = require('getContentStateFragment');
+const nullthrows = require('nullthrows');
 
-var clipboard: ?BlockMap = null;
+let clipboard: ?BlockMap = null;
 
 /**
  * Some systems offer a "secondary" clipboard to allow quick internal cut
  * and paste behavior. For instance, Ctrl+K (cut) and Ctrl+Y (paste).
  */
-var SecondaryClipboard = {
+const SecondaryClipboard = {
   cut: function(editorState: EditorState): EditorState {
-    var content = editorState.getCurrentContent();
-    var selection = editorState.getSelection();
-    var targetRange: ?SelectionState = null;
+    const content = editorState.getCurrentContent();
+    const selection = editorState.getSelection();
+    let targetRange: ?SelectionState = null;
 
     if (selection.isCollapsed()) {
-      var anchorKey = selection.getAnchorKey();
-      var blockEnd = content.getBlockForKey(anchorKey).getLength();
+      const anchorKey = selection.getAnchorKey();
+      const blockEnd = content.getBlockForKey(anchorKey).getLength();
 
       if (blockEnd === selection.getAnchorOffset()) {
         return editorState;
@@ -49,7 +49,7 @@ var SecondaryClipboard = {
     targetRange = nullthrows(targetRange);
     clipboard = getContentStateFragment(content, targetRange);
 
-    var afterRemoval = DraftModifier.removeRange(
+    const afterRemoval = DraftModifier.removeRange(
       content,
       targetRange,
       'forward',
@@ -67,7 +67,7 @@ var SecondaryClipboard = {
       return editorState;
     }
 
-    var newContent = DraftModifier.replaceWithFragment(
+    const newContent = DraftModifier.replaceWithFragment(
       editorState.getCurrentContent(),
       editorState.getSelection(),
       clipboard,
diff --git a/src/component/handlers/edit/commands/keyCommandBackspaceToStartOfLine.js b/src/component/handlers/edit/commands/keyCommandBackspaceToStartOfLine.js
index 3442cc0f3d..8027c1b332 100644
--- a/src/component/handlers/edit/commands/keyCommandBackspaceToStartOfLine.js
+++ b/src/component/handlers/edit/commands/keyCommandBackspaceToStartOfLine.js
@@ -12,17 +12,17 @@
 
 'use strict';
 
-var EditorState = require('EditorState');
+const EditorState = require('EditorState');
 
-var expandRangeToStartOfLine = require('expandRangeToStartOfLine');
-var getDraftEditorSelectionWithNodes = require('getDraftEditorSelectionWithNodes');
-var moveSelectionBackward = require('moveSelectionBackward');
-var removeTextWithStrategy = require('removeTextWithStrategy');
+const expandRangeToStartOfLine = require('expandRangeToStartOfLine');
+const getDraftEditorSelectionWithNodes = require('getDraftEditorSelectionWithNodes');
+const moveSelectionBackward = require('moveSelectionBackward');
+const removeTextWithStrategy = require('removeTextWithStrategy');
 
 function keyCommandBackspaceToStartOfLine(
   editorState: EditorState,
 ): EditorState {
-  var afterRemoval = removeTextWithStrategy(
+  const afterRemoval = removeTextWithStrategy(
     editorState,
     strategyState => {
       const selection = strategyState.getSelection();
@@ -30,8 +30,8 @@ function keyCommandBackspaceToStartOfLine(
         return moveSelectionBackward(strategyState, 1);
       }
 
-      var domSelection = global.getSelection();
-      var range = domSelection.getRangeAt(0);
+      const domSelection = global.getSelection();
+      let range = domSelection.getRangeAt(0);
       range = expandRangeToStartOfLine(range);
 
       return getDraftEditorSelectionWithNodes(
diff --git a/src/component/handlers/edit/commands/keyCommandBackspaceWord.js b/src/component/handlers/edit/commands/keyCommandBackspaceWord.js
index 42bb802483..e42b656178 100644
--- a/src/component/handlers/edit/commands/keyCommandBackspaceWord.js
+++ b/src/component/handlers/edit/commands/keyCommandBackspaceWord.js
@@ -12,33 +12,33 @@
 
 'use strict';
 
-var DraftRemovableWord = require('DraftRemovableWord');
-var EditorState = require('EditorState');
+const DraftRemovableWord = require('DraftRemovableWord');
+const EditorState = require('EditorState');
 
-var moveSelectionBackward = require('moveSelectionBackward');
-var removeTextWithStrategy = require('removeTextWithStrategy');
+const moveSelectionBackward = require('moveSelectionBackward');
+const removeTextWithStrategy = require('removeTextWithStrategy');
 
 /**
  * Delete the word that is left of the cursor, as well as any spaces or
  * punctuation after the word.
  */
 function keyCommandBackspaceWord(editorState: EditorState): EditorState {
-  var afterRemoval = removeTextWithStrategy(
+  const afterRemoval = removeTextWithStrategy(
     editorState,
     strategyState => {
-      var selection = strategyState.getSelection();
-      var offset = selection.getStartOffset();
+      const selection = strategyState.getSelection();
+      const offset = selection.getStartOffset();
       // If there are no words before the cursor, remove the preceding newline.
       if (offset === 0) {
         return moveSelectionBackward(strategyState, 1);
       }
-      var key = selection.getStartKey();
-      var content = strategyState.getCurrentContent();
-      var text = content
+      const key = selection.getStartKey();
+      const content = strategyState.getCurrentContent();
+      const text = content
         .getBlockForKey(key)
         .getText()
         .slice(0, offset);
-      var toRemove = DraftRemovableWord.getBackward(text);
+      const toRemove = DraftRemovableWord.getBackward(text);
       return moveSelectionBackward(strategyState, toRemove.length || 1);
     },
     'backward',
diff --git a/src/component/handlers/edit/commands/keyCommandDeleteWord.js b/src/component/handlers/edit/commands/keyCommandDeleteWord.js
index 34468728fb..4b196e089a 100644
--- a/src/component/handlers/edit/commands/keyCommandDeleteWord.js
+++ b/src/component/handlers/edit/commands/keyCommandDeleteWord.js
@@ -12,29 +12,29 @@
 
 'use strict';
 
-var DraftRemovableWord = require('DraftRemovableWord');
-var EditorState = require('EditorState');
+const DraftRemovableWord = require('DraftRemovableWord');
+const EditorState = require('EditorState');
 
-var moveSelectionForward = require('moveSelectionForward');
-var removeTextWithStrategy = require('removeTextWithStrategy');
+const moveSelectionForward = require('moveSelectionForward');
+const removeTextWithStrategy = require('removeTextWithStrategy');
 
 /**
  * Delete the word that is right of the cursor, as well as any spaces or
  * punctuation before the word.
  */
 function keyCommandDeleteWord(editorState: EditorState): EditorState {
-  var afterRemoval = removeTextWithStrategy(
+  const afterRemoval = removeTextWithStrategy(
     editorState,
     strategyState => {
-      var selection = strategyState.getSelection();
-      var offset = selection.getStartOffset();
-      var key = selection.getStartKey();
-      var content = strategyState.getCurrentContent();
-      var text = content
+      const selection = strategyState.getSelection();
+      const offset = selection.getStartOffset();
+      const key = selection.getStartKey();
+      const content = strategyState.getCurrentContent();
+      const text = content
         .getBlockForKey(key)
         .getText()
         .slice(offset);
-      var toRemove = DraftRemovableWord.getForward(text);
+      const toRemove = DraftRemovableWord.getForward(text);
 
       // If there are no words in front of the cursor, remove the newline.
       return moveSelectionForward(strategyState, toRemove.length || 1);
diff --git a/src/component/handlers/edit/commands/keyCommandInsertNewline.js b/src/component/handlers/edit/commands/keyCommandInsertNewline.js
index eb183991e0..2822fe5131 100644
--- a/src/component/handlers/edit/commands/keyCommandInsertNewline.js
+++ b/src/component/handlers/edit/commands/keyCommandInsertNewline.js
@@ -12,11 +12,11 @@
 
 'use strict';
 
-var DraftModifier = require('DraftModifier');
-var EditorState = require('EditorState');
+const DraftModifier = require('DraftModifier');
+const EditorState = require('EditorState');
 
 function keyCommandInsertNewline(editorState: EditorState): EditorState {
-  var contentState = DraftModifier.splitBlock(
+  const contentState = DraftModifier.splitBlock(
     editorState.getCurrentContent(),
     editorState.getSelection(),
   );
diff --git a/src/component/handlers/edit/commands/keyCommandMoveSelectionToEndOfBlock.js b/src/component/handlers/edit/commands/keyCommandMoveSelectionToEndOfBlock.js
index e30ee2c302..48127a3fa9 100644
--- a/src/component/handlers/edit/commands/keyCommandMoveSelectionToEndOfBlock.js
+++ b/src/component/handlers/edit/commands/keyCommandMoveSelectionToEndOfBlock.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var EditorState = require('EditorState');
+const EditorState = require('EditorState');
 
 /**
  * See comment for `moveSelectionToStartOfBlock`.
@@ -20,10 +20,10 @@ var EditorState = require('EditorState');
 function keyCommandMoveSelectionToEndOfBlock(
   editorState: EditorState,
 ): EditorState {
-  var selection = editorState.getSelection();
-  var endKey = selection.getEndKey();
-  var content = editorState.getCurrentContent();
-  var textLength = content.getBlockForKey(endKey).getLength();
+  const selection = editorState.getSelection();
+  const endKey = selection.getEndKey();
+  const content = editorState.getCurrentContent();
+  const textLength = content.getBlockForKey(endKey).getLength();
   return EditorState.set(editorState, {
     selection: selection.merge({
       anchorKey: endKey,
diff --git a/src/component/handlers/edit/commands/keyCommandMoveSelectionToStartOfBlock.js b/src/component/handlers/edit/commands/keyCommandMoveSelectionToStartOfBlock.js
index 32069c1251..fcd36618b7 100644
--- a/src/component/handlers/edit/commands/keyCommandMoveSelectionToStartOfBlock.js
+++ b/src/component/handlers/edit/commands/keyCommandMoveSelectionToStartOfBlock.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var EditorState = require('EditorState');
+const EditorState = require('EditorState');
 
 /**
  * Collapse selection at the start of the first selected block. This is used
@@ -22,8 +22,8 @@ var EditorState = require('EditorState');
 function keyCommandMoveSelectionToStartOfBlock(
   editorState: EditorState,
 ): EditorState {
-  var selection = editorState.getSelection();
-  var startKey = selection.getStartKey();
+  const selection = editorState.getSelection();
+  const startKey = selection.getStartKey();
   return EditorState.set(editorState, {
     selection: selection.merge({
       anchorKey: startKey,
diff --git a/src/component/handlers/edit/commands/keyCommandPlainBackspace.js b/src/component/handlers/edit/commands/keyCommandPlainBackspace.js
index 4bd966534a..f87b872d48 100644
--- a/src/component/handlers/edit/commands/keyCommandPlainBackspace.js
+++ b/src/component/handlers/edit/commands/keyCommandPlainBackspace.js
@@ -12,11 +12,11 @@
 
 'use strict';
 
-var EditorState = require('EditorState');
-var UnicodeUtils = require('UnicodeUtils');
+const EditorState = require('EditorState');
+const UnicodeUtils = require('UnicodeUtils');
 
-var moveSelectionBackward = require('moveSelectionBackward');
-var removeTextWithStrategy = require('removeTextWithStrategy');
+const moveSelectionBackward = require('moveSelectionBackward');
+const removeTextWithStrategy = require('removeTextWithStrategy');
 
 /**
  * Remove the selected range. If the cursor is collapsed, remove the preceding
@@ -24,14 +24,14 @@ var removeTextWithStrategy = require('removeTextWithStrategy');
  * will remove a surrogate pair properly as well.
  */
 function keyCommandPlainBackspace(editorState: EditorState): EditorState {
-  var afterRemoval = removeTextWithStrategy(
+  const afterRemoval = removeTextWithStrategy(
     editorState,
     strategyState => {
-      var selection = strategyState.getSelection();
-      var content = strategyState.getCurrentContent();
-      var key = selection.getAnchorKey();
-      var offset = selection.getAnchorOffset();
-      var charBehind = content.getBlockForKey(key).getText()[offset - 1];
+      const selection = strategyState.getSelection();
+      const content = strategyState.getCurrentContent();
+      const key = selection.getAnchorKey();
+      const offset = selection.getAnchorOffset();
+      const charBehind = content.getBlockForKey(key).getText()[offset - 1];
       return moveSelectionBackward(
         strategyState,
         charBehind ? UnicodeUtils.getUTF16Length(charBehind, 0) : 1,
@@ -44,7 +44,7 @@ function keyCommandPlainBackspace(editorState: EditorState): EditorState {
     return editorState;
   }
 
-  var selection = editorState.getSelection();
+  const selection = editorState.getSelection();
   return EditorState.push(
     editorState,
     afterRemoval.set('selectionBefore', selection),
diff --git a/src/component/handlers/edit/commands/keyCommandPlainDelete.js b/src/component/handlers/edit/commands/keyCommandPlainDelete.js
index c353c83349..a8cd73f81e 100644
--- a/src/component/handlers/edit/commands/keyCommandPlainDelete.js
+++ b/src/component/handlers/edit/commands/keyCommandPlainDelete.js
@@ -12,11 +12,11 @@
 
 'use strict';
 
-var EditorState = require('EditorState');
-var UnicodeUtils = require('UnicodeUtils');
+const EditorState = require('EditorState');
+const UnicodeUtils = require('UnicodeUtils');
 
-var moveSelectionForward = require('moveSelectionForward');
-var removeTextWithStrategy = require('removeTextWithStrategy');
+const moveSelectionForward = require('moveSelectionForward');
+const removeTextWithStrategy = require('removeTextWithStrategy');
 
 /**
  * Remove the selected range. If the cursor is collapsed, remove the following
@@ -24,14 +24,14 @@ var removeTextWithStrategy = require('removeTextWithStrategy');
  * will remove a surrogate pair properly as well.
  */
 function keyCommandPlainDelete(editorState: EditorState): EditorState {
-  var afterRemoval = removeTextWithStrategy(
+  const afterRemoval = removeTextWithStrategy(
     editorState,
     strategyState => {
-      var selection = strategyState.getSelection();
-      var content = strategyState.getCurrentContent();
-      var key = selection.getAnchorKey();
-      var offset = selection.getAnchorOffset();
-      var charAhead = content.getBlockForKey(key).getText()[offset];
+      const selection = strategyState.getSelection();
+      const content = strategyState.getCurrentContent();
+      const key = selection.getAnchorKey();
+      const offset = selection.getAnchorOffset();
+      const charAhead = content.getBlockForKey(key).getText()[offset];
       return moveSelectionForward(
         strategyState,
         charAhead ? UnicodeUtils.getUTF16Length(charAhead, 0) : 1,
@@ -44,7 +44,7 @@ function keyCommandPlainDelete(editorState: EditorState): EditorState {
     return editorState;
   }
 
-  var selection = editorState.getSelection();
+  const selection = editorState.getSelection();
 
   return EditorState.push(
     editorState,
diff --git a/src/component/handlers/edit/commands/keyCommandTransposeCharacters.js b/src/component/handlers/edit/commands/keyCommandTransposeCharacters.js
index 205a06f112..efcab2924d 100644
--- a/src/component/handlers/edit/commands/keyCommandTransposeCharacters.js
+++ b/src/component/handlers/edit/commands/keyCommandTransposeCharacters.js
@@ -12,10 +12,10 @@
 
 'use strict';
 
-var DraftModifier = require('DraftModifier');
-var EditorState = require('EditorState');
+const DraftModifier = require('DraftModifier');
+const EditorState = require('EditorState');
 
-var getContentStateFragment = require('getContentStateFragment');
+const getContentStateFragment = require('getContentStateFragment');
 
 /**
  * Transpose the characters on either side of a collapsed cursor, or
@@ -23,28 +23,28 @@ var getContentStateFragment = require('getContentStateFragment');
  * characters.
  */
 function keyCommandTransposeCharacters(editorState: EditorState): EditorState {
-  var selection = editorState.getSelection();
+  const selection = editorState.getSelection();
   if (!selection.isCollapsed()) {
     return editorState;
   }
 
-  var offset = selection.getAnchorOffset();
+  const offset = selection.getAnchorOffset();
   if (offset === 0) {
     return editorState;
   }
 
-  var blockKey = selection.getAnchorKey();
-  var content = editorState.getCurrentContent();
-  var block = content.getBlockForKey(blockKey);
-  var length = block.getLength();
+  const blockKey = selection.getAnchorKey();
+  const content = editorState.getCurrentContent();
+  const block = content.getBlockForKey(blockKey);
+  const length = block.getLength();
 
   // Nothing to transpose if there aren't two characters.
   if (length <= 1) {
     return editorState;
   }
 
-  var removalRange;
-  var finalSelection;
+  let removalRange;
+  let finalSelection;
 
   if (offset === length) {
     // The cursor is at the end of the block. Swap the last two characters.
@@ -57,28 +57,28 @@ function keyCommandTransposeCharacters(editorState: EditorState): EditorState {
 
   // Extract the character to move as a fragment. This preserves its
   // styling and entity, if any.
-  var movedFragment = getContentStateFragment(content, removalRange);
-  var afterRemoval = DraftModifier.removeRange(
+  const movedFragment = getContentStateFragment(content, removalRange);
+  const afterRemoval = DraftModifier.removeRange(
     content,
     removalRange,
     'backward',
   );
 
   // After the removal, the insertion target is one character back.
-  var selectionAfter = afterRemoval.getSelectionAfter();
-  var targetOffset = selectionAfter.getAnchorOffset() - 1;
-  var targetRange = selectionAfter.merge({
+  const selectionAfter = afterRemoval.getSelectionAfter();
+  const targetOffset = selectionAfter.getAnchorOffset() - 1;
+  const targetRange = selectionAfter.merge({
     anchorOffset: targetOffset,
     focusOffset: targetOffset,
   });
 
-  var afterInsert = DraftModifier.replaceWithFragment(
+  const afterInsert = DraftModifier.replaceWithFragment(
     afterRemoval,
     targetRange,
     movedFragment,
   );
 
-  var newEditorState = EditorState.push(
+  const newEditorState = EditorState.push(
     editorState,
     afterInsert,
     'insert-fragment',
diff --git a/src/component/handlers/edit/commands/keyCommandUndo.js b/src/component/handlers/edit/commands/keyCommandUndo.js
index 7fb1728179..0a3ebf56ca 100644
--- a/src/component/handlers/edit/commands/keyCommandUndo.js
+++ b/src/component/handlers/edit/commands/keyCommandUndo.js
@@ -12,21 +12,21 @@
 
 'use strict';
 
-var EditorState = require('EditorState');
+const EditorState = require('EditorState');
 
 function keyCommandUndo(
   e: SyntheticKeyboardEvent<>,
   editorState: EditorState,
   updateFn: (editorState: EditorState) => void,
 ): void {
-  var undoneState = EditorState.undo(editorState);
+  const undoneState = EditorState.undo(editorState);
 
   // If the last change to occur was a spellcheck change, allow the undo
   // event to fall through to the browser. This allows the browser to record
   // the unwanted change, which should soon lead it to learn not to suggest
   // the correction again.
   if (editorState.getLastChangeType() === 'spellcheck-change') {
-    var nativelyRenderedContent = undoneState.getCurrentContent();
+    const nativelyRenderedContent = undoneState.getCurrentContent();
     updateFn(EditorState.set(undoneState, {nativelyRenderedContent}));
     return;
   }
diff --git a/src/component/handlers/edit/commands/moveSelectionBackward.js b/src/component/handlers/edit/commands/moveSelectionBackward.js
index 855e561505..7fecd14b2f 100644
--- a/src/component/handlers/edit/commands/moveSelectionBackward.js
+++ b/src/component/handlers/edit/commands/moveSelectionBackward.js
@@ -27,21 +27,21 @@ function moveSelectionBackward(
   editorState: EditorState,
   maxDistance: number,
 ): SelectionState {
-  var selection = editorState.getSelection();
-  var content = editorState.getCurrentContent();
-  var key = selection.getStartKey();
-  var offset = selection.getStartOffset();
+  const selection = editorState.getSelection();
+  const content = editorState.getCurrentContent();
+  const key = selection.getStartKey();
+  const offset = selection.getStartOffset();
 
-  var focusKey = key;
-  var focusOffset = 0;
+  let focusKey = key;
+  let focusOffset = 0;
 
   if (maxDistance > offset) {
-    var keyBefore = content.getKeyBefore(key);
+    const keyBefore = content.getKeyBefore(key);
     if (keyBefore == null) {
       focusKey = key;
     } else {
       focusKey = keyBefore;
-      var blockBefore = content.getBlockForKey(keyBefore);
+      const blockBefore = content.getBlockForKey(keyBefore);
       focusOffset = blockBefore.getText().length;
     }
   } else {
diff --git a/src/component/handlers/edit/commands/moveSelectionForward.js b/src/component/handlers/edit/commands/moveSelectionForward.js
index c6fa3e2939..ca8d722e3e 100644
--- a/src/component/handlers/edit/commands/moveSelectionForward.js
+++ b/src/component/handlers/edit/commands/moveSelectionForward.js
@@ -27,15 +27,15 @@ function moveSelectionForward(
   editorState: EditorState,
   maxDistance: number,
 ): SelectionState {
-  var selection = editorState.getSelection();
-  var key = selection.getStartKey();
-  var offset = selection.getStartOffset();
-  var content = editorState.getCurrentContent();
+  const selection = editorState.getSelection();
+  const key = selection.getStartKey();
+  const offset = selection.getStartOffset();
+  const content = editorState.getCurrentContent();
 
-  var focusKey = key;
-  var focusOffset;
+  let focusKey = key;
+  let focusOffset;
 
-  var block = content.getBlockForKey(key);
+  const block = content.getBlockForKey(key);
 
   if (maxDistance > block.getText().length - offset) {
     focusKey = content.getKeyAfter(key);
diff --git a/src/component/handlers/edit/commands/removeTextWithStrategy.js b/src/component/handlers/edit/commands/removeTextWithStrategy.js
index b26da7dc77..f2a00536c2 100644
--- a/src/component/handlers/edit/commands/removeTextWithStrategy.js
+++ b/src/component/handlers/edit/commands/removeTextWithStrategy.js
@@ -17,7 +17,7 @@ import type {DraftRemovalDirection} from 'DraftRemovalDirection';
 import type EditorState from 'EditorState';
 import type SelectionState from 'SelectionState';
 
-var DraftModifier = require('DraftModifier');
+const DraftModifier = require('DraftModifier');
 
 /**
  * For a collapsed selection state, remove text based on the specified strategy.
@@ -28,9 +28,9 @@ function removeTextWithStrategy(
   strategy: (editorState: EditorState) => SelectionState,
   direction: DraftRemovalDirection,
 ): ContentState {
-  var selection = editorState.getSelection();
-  var content = editorState.getCurrentContent();
-  var target = selection;
+  const selection = editorState.getSelection();
+  const content = editorState.getCurrentContent();
+  let target = selection;
   if (selection.isCollapsed()) {
     if (direction === 'forward') {
       if (editorState.isSelectionAtEndOfContent()) {
diff --git a/src/component/handlers/edit/editOnBeforeInput.js b/src/component/handlers/edit/editOnBeforeInput.js
index 6bf02e1595..425a60ad83 100644
--- a/src/component/handlers/edit/editOnBeforeInput.js
+++ b/src/component/handlers/edit/editOnBeforeInput.js
@@ -15,16 +15,16 @@
 import type DraftEditor from 'DraftEditor.react';
 import type {DraftInlineStyle} from 'DraftInlineStyle';
 
-var BlockTree = require('BlockTree');
-var DraftModifier = require('DraftModifier');
-var EditorState = require('EditorState');
-var UserAgent = require('UserAgent');
+const BlockTree = require('BlockTree');
+const DraftModifier = require('DraftModifier');
+const EditorState = require('EditorState');
+const UserAgent = require('UserAgent');
 
-var getEntityKeyForSelection = require('getEntityKeyForSelection');
+const getEntityKeyForSelection = require('getEntityKeyForSelection');
 const isEventHandled = require('isEventHandled');
-var isSelectionAtLeafStart = require('isSelectionAtLeafStart');
-var nullthrows = require('nullthrows');
-var setImmediate = require('setImmediate');
+const isSelectionAtLeafStart = require('isSelectionAtLeafStart');
+const nullthrows = require('nullthrows');
+const setImmediate = require('setImmediate');
 
 // When nothing is focused, Firefox regards two characters, `'` and `/`, as
 // commands that should open and focus the "quickfind" search bar. This should
@@ -33,9 +33,9 @@ var setImmediate = require('setImmediate');
 // This breaks the input. Special case these characters to ensure that when
 // they are typed, we prevent default on the event to make sure not to
 // trigger quickfind.
-var FF_QUICKFIND_CHAR = "'";
-var FF_QUICKFIND_LINK_CHAR = '/';
-var isFirefox = UserAgent.isBrowser('Firefox');
+const FF_QUICKFIND_CHAR = "'";
+const FF_QUICKFIND_LINK_CHAR = '/';
+const isFirefox = UserAgent.isBrowser('Firefox');
 
 function mustPreventDefaultForCharacter(character: string): boolean {
   return (
@@ -54,7 +54,7 @@ function replaceText(
   inlineStyle: DraftInlineStyle,
   entityKey: ?string,
 ): EditorState {
-  var contentState = DraftModifier.replaceText(
+  const contentState = DraftModifier.replaceText(
     editorState.getCurrentContent(),
     editorState.getSelection(),
     text,
@@ -84,7 +84,7 @@ function editOnBeforeInput(
 
   const editorState = editor._latestEditorState;
 
-  var chars = e.data;
+  const chars = e.data;
 
   // In some cases (ex: IE ideographic space insertion) no character data
   // is provided. There's nothing to do when this happens.
@@ -108,10 +108,10 @@ function editOnBeforeInput(
   // If selection is collapsed, conditionally allow native behavior. This
   // reduces re-renders and preserves spellcheck highlighting. If the selection
   // is not collapsed, we will re-render.
-  var selection = editorState.getSelection();
-  var selectionStart = selection.getStartOffset();
-  var selectionEnd = selection.getEndOffset();
-  var anchorKey = selection.getAnchorKey();
+  const selection = editorState.getSelection();
+  const selectionStart = selection.getStartOffset();
+  const selectionEnd = selection.getEndOffset();
+  const anchorKey = selection.getAnchorKey();
 
   if (!selection.isCollapsed()) {
     e.preventDefault();
@@ -119,7 +119,7 @@ function editOnBeforeInput(
     // If the currently selected text matches what the user is trying to
     // replace it with, let's just update the `SelectionState`. If not, update
     // the `ContentState` with the new text.
-    var currentlySelectedChars = editorState
+    const currentlySelectedChars = editorState
       .getCurrentContent()
       .getPlainText()
       .slice(selectionStart, selectionEnd);
@@ -149,7 +149,7 @@ function editOnBeforeInput(
     return;
   }
 
-  var newEditorState = replaceText(
+  let newEditorState = replaceText(
     editorState,
     chars,
     editorState.getCurrentInlineStyle(),
@@ -190,10 +190,10 @@ function editOnBeforeInput(
     // Check the old and new "fingerprints" of the current block to determine
     // whether this insertion requires any addition or removal of text nodes,
     // in which case we would prevent the native character insertion.
-    var originalFingerprint = BlockTree.getFingerprint(
+    const originalFingerprint = BlockTree.getFingerprint(
       editorState.getBlockTree(anchorKey),
     );
-    var newFingerprint = BlockTree.getFingerprint(
+    const newFingerprint = BlockTree.getFingerprint(
       newEditorState.getBlockTree(anchorKey),
     );
     mustPreventNative = originalFingerprint !== newFingerprint;
diff --git a/src/component/handlers/edit/editOnBlur.js b/src/component/handlers/edit/editOnBlur.js
index 5463cf3689..11a3d86cd7 100644
--- a/src/component/handlers/edit/editOnBlur.js
+++ b/src/component/handlers/edit/editOnBlur.js
@@ -40,13 +40,13 @@ function editOnBlur(editor: DraftEditor, e: SyntheticEvent<>): void {
     }
   }
 
-  var editorState = editor._latestEditorState;
-  var currentSelection = editorState.getSelection();
+  const editorState = editor._latestEditorState;
+  const currentSelection = editorState.getSelection();
   if (!currentSelection.getHasFocus()) {
     return;
   }
 
-  var selection = currentSelection.set('hasFocus', false);
+  const selection = currentSelection.set('hasFocus', false);
   editor.props.onBlur && editor.props.onBlur(e);
   editor.update(EditorState.acceptSelection(editorState, selection));
 }
diff --git a/src/component/handlers/edit/editOnCompositionStart.js b/src/component/handlers/edit/editOnCompositionStart.js
index fc14fd2e6c..201486f426 100644
--- a/src/component/handlers/edit/editOnCompositionStart.js
+++ b/src/component/handlers/edit/editOnCompositionStart.js
@@ -14,7 +14,7 @@
 
 import type DraftEditor from 'DraftEditor.react';
 
-var EditorState = require('EditorState');
+const EditorState = require('EditorState');
 
 /**
  * The user has begun using an IME input system. Switching to `composite` mode
diff --git a/src/component/handlers/edit/editOnCopy.js b/src/component/handlers/edit/editOnCopy.js
index 0155c31f15..605532e70a 100644
--- a/src/component/handlers/edit/editOnCopy.js
+++ b/src/component/handlers/edit/editOnCopy.js
@@ -14,7 +14,7 @@
 
 import type DraftEditor from 'DraftEditor.react';
 
-var getFragmentFromSelection = require('getFragmentFromSelection');
+const getFragmentFromSelection = require('getFragmentFromSelection');
 
 /**
  * If we have a selection, create a ContentState fragment and store
@@ -22,8 +22,8 @@ var getFragmentFromSelection = require('getFragmentFromSelection');
  * fragment if no external clipboard data is supplied.
  */
 function editOnCopy(editor: DraftEditor, e: SyntheticClipboardEvent<>): void {
-  var editorState = editor._latestEditorState;
-  var selection = editorState.getSelection();
+  const editorState = editor._latestEditorState;
+  const selection = editorState.getSelection();
 
   // No selection, so there's nothing to copy.
   if (selection.isCollapsed()) {
diff --git a/src/component/handlers/edit/editOnFocus.js b/src/component/handlers/edit/editOnFocus.js
index 33bd0e9099..eb12d12a69 100644
--- a/src/component/handlers/edit/editOnFocus.js
+++ b/src/component/handlers/edit/editOnFocus.js
@@ -14,17 +14,17 @@
 
 import type DraftEditor from 'DraftEditor.react';
 
-var EditorState = require('EditorState');
-var UserAgent = require('UserAgent');
+const EditorState = require('EditorState');
+const UserAgent = require('UserAgent');
 
 function editOnFocus(editor: DraftEditor, e: SyntheticFocusEvent<>): void {
-  var editorState = editor._latestEditorState;
-  var currentSelection = editorState.getSelection();
+  const editorState = editor._latestEditorState;
+  const currentSelection = editorState.getSelection();
   if (currentSelection.getHasFocus()) {
     return;
   }
 
-  var selection = currentSelection.set('hasFocus', true);
+  const selection = currentSelection.set('hasFocus', true);
   editor.props.onFocus && editor.props.onFocus(e);
 
   // When the tab containing this text editor is hidden and the user does a
diff --git a/src/component/handlers/edit/editOnInput.js b/src/component/handlers/edit/editOnInput.js
index aa7a7c9d2f..0e481fc41e 100644
--- a/src/component/handlers/edit/editOnInput.js
+++ b/src/component/handlers/edit/editOnInput.js
@@ -14,18 +14,18 @@
 
 import type DraftEditor from 'DraftEditor.react';
 
-var DraftModifier = require('DraftModifier');
-var DraftOffsetKey = require('DraftOffsetKey');
-var EditorState = require('EditorState');
-var UserAgent = require('UserAgent');
+const DraftModifier = require('DraftModifier');
+const DraftOffsetKey = require('DraftOffsetKey');
+const EditorState = require('EditorState');
+const UserAgent = require('UserAgent');
 
-var findAncestorOffsetKey = require('findAncestorOffsetKey');
+const findAncestorOffsetKey = require('findAncestorOffsetKey');
 const gkx = require('gkx');
-var nullthrows = require('nullthrows');
+const nullthrows = require('nullthrows');
 
-var isGecko = UserAgent.isEngine('Gecko');
+const isGecko = UserAgent.isEngine('Gecko');
 
-var DOUBLE_NEWLINE = '\n\n';
+const DOUBLE_NEWLINE = '\n\n';
 
 /**
  * This function is intended to handle spellcheck and autocorrect changes,
@@ -45,9 +45,9 @@ function editOnInput(editor: DraftEditor): void {
     editor._pendingStateFromBeforeInput = undefined;
   }
 
-  var domSelection = global.getSelection();
+  const domSelection = global.getSelection();
 
-  var {anchorNode, isCollapsed} = domSelection;
+  const {anchorNode, isCollapsed} = domSelection;
   const isNotTextNode = anchorNode.nodeType !== Node.TEXT_NODE;
   const isNotTextOrElementNode =
     anchorNode.nodeType !== Node.TEXT_NODE &&
@@ -85,18 +85,18 @@ function editOnInput(editor: DraftEditor): void {
     }
   }
 
-  var domText = anchorNode.textContent;
-  var editorState = editor._latestEditorState;
-  var offsetKey = nullthrows(findAncestorOffsetKey(anchorNode));
-  var {blockKey, decoratorKey, leafKey} = DraftOffsetKey.decode(offsetKey);
+  let domText = anchorNode.textContent;
+  const editorState = editor._latestEditorState;
+  const offsetKey = nullthrows(findAncestorOffsetKey(anchorNode));
+  const {blockKey, decoratorKey, leafKey} = DraftOffsetKey.decode(offsetKey);
 
-  var {start, end} = editorState
+  const {start, end} = editorState
     .getBlockTree(blockKey)
     .getIn([decoratorKey, 'leaves', leafKey]);
 
-  var content = editorState.getCurrentContent();
-  var block = content.getBlockForKey(blockKey);
-  var modelText = block.getText().slice(start, end);
+  const content = editorState.getCurrentContent();
+  const block = content.getBlockForKey(blockKey);
+  const modelText = block.getText().slice(start, end);
 
   // Special-case soft newlines here. If the DOM text ends in a soft newline,
   // we will have manually inserted an extra soft newline in DraftEditorLeaf.
@@ -115,10 +115,10 @@ function editOnInput(editor: DraftEditor): void {
     return;
   }
 
-  var selection = editorState.getSelection();
+  const selection = editorState.getSelection();
 
   // We'll replace the entire leaf with the text content of the target.
-  var targetRange = selection.merge({
+  const targetRange = selection.merge({
     anchorOffset: start,
     focusOffset: end,
     isBackward: false,
@@ -143,7 +143,7 @@ function editOnInput(editor: DraftEditor): void {
     preserveEntity ? block.getEntityAt(start) : null,
   );
 
-  var anchorOffset, focusOffset, startOffset, endOffset;
+  let anchorOffset, focusOffset, startOffset, endOffset;
 
   if (isGecko) {
     // Firefox selection does not change while the context menu is open, so
@@ -160,7 +160,7 @@ function editOnInput(editor: DraftEditor): void {
     // DOM selection. Don't trust it. Instead, use our existing SelectionState
     // and adjust it based on the number of characters changed during the
     // mutation.
-    var charDelta = domText.length - modelText.length;
+    const charDelta = domText.length - modelText.length;
     startOffset = selection.getStartOffset();
     endOffset = selection.getEndOffset();
 
@@ -171,7 +171,7 @@ function editOnInput(editor: DraftEditor): void {
   // Segmented entities are completely or partially removed when their
   // text content changes. For this case we do not want any text to be selected
   // after the change, so we are not merging the selection.
-  var contentWithAdjustedDOMSelection = newContent.merge({
+  const contentWithAdjustedDOMSelection = newContent.merge({
     selectionBefore: content.getSelectionAfter(),
     selectionAfter: selection.merge({anchorOffset, focusOffset}),
   });
diff --git a/src/component/handlers/edit/editOnKeyDown.js b/src/component/handlers/edit/editOnKeyDown.js
index 7cdcef70d2..4f48a0551f 100644
--- a/src/component/handlers/edit/editOnKeyDown.js
+++ b/src/component/handlers/edit/editOnKeyDown.js
@@ -15,27 +15,27 @@
 import type DraftEditor from 'DraftEditor.react';
 import type {DraftEditorCommand} from 'DraftEditorCommand';
 
-var DraftModifier = require('DraftModifier');
-var EditorState = require('EditorState');
-var KeyBindingUtil = require('KeyBindingUtil');
-var Keys = require('Keys');
-var SecondaryClipboard = require('SecondaryClipboard');
-var UserAgent = require('UserAgent');
+const DraftModifier = require('DraftModifier');
+const EditorState = require('EditorState');
+const KeyBindingUtil = require('KeyBindingUtil');
+const Keys = require('Keys');
+const SecondaryClipboard = require('SecondaryClipboard');
+const UserAgent = require('UserAgent');
 
 const isEventHandled = require('isEventHandled');
-var keyCommandBackspaceToStartOfLine = require('keyCommandBackspaceToStartOfLine');
-var keyCommandBackspaceWord = require('keyCommandBackspaceWord');
-var keyCommandDeleteWord = require('keyCommandDeleteWord');
-var keyCommandInsertNewline = require('keyCommandInsertNewline');
-var keyCommandMoveSelectionToEndOfBlock = require('keyCommandMoveSelectionToEndOfBlock');
-var keyCommandMoveSelectionToStartOfBlock = require('keyCommandMoveSelectionToStartOfBlock');
-var keyCommandPlainBackspace = require('keyCommandPlainBackspace');
-var keyCommandPlainDelete = require('keyCommandPlainDelete');
-var keyCommandTransposeCharacters = require('keyCommandTransposeCharacters');
-var keyCommandUndo = require('keyCommandUndo');
+const keyCommandBackspaceToStartOfLine = require('keyCommandBackspaceToStartOfLine');
+const keyCommandBackspaceWord = require('keyCommandBackspaceWord');
+const keyCommandDeleteWord = require('keyCommandDeleteWord');
+const keyCommandInsertNewline = require('keyCommandInsertNewline');
+const keyCommandMoveSelectionToEndOfBlock = require('keyCommandMoveSelectionToEndOfBlock');
+const keyCommandMoveSelectionToStartOfBlock = require('keyCommandMoveSelectionToStartOfBlock');
+const keyCommandPlainBackspace = require('keyCommandPlainBackspace');
+const keyCommandPlainDelete = require('keyCommandPlainDelete');
+const keyCommandTransposeCharacters = require('keyCommandTransposeCharacters');
+const keyCommandUndo = require('keyCommandUndo');
 
-var {isOptionKeyCommand} = KeyBindingUtil;
-var isChrome = UserAgent.isBrowser('Chrome');
+const {isOptionKeyCommand} = KeyBindingUtil;
+const isChrome = UserAgent.isBrowser('Chrome');
 
 /**
  * Map a `DraftEditorCommand` command value to a corresponding function.
@@ -84,8 +84,8 @@ function onKeyCommand(
  * component may provide a custom mapping via the `keyBindingFn` prop.
  */
 function editOnKeyDown(editor: DraftEditor, e: SyntheticKeyboardEvent<>): void {
-  var keyCode = e.which;
-  var editorState = editor._latestEditorState;
+  const keyCode = e.which;
+  const editorState = editor._latestEditorState;
   function callDeprecatedHandler(
     handlerName:
       | 'onDownArrow'
@@ -163,7 +163,7 @@ function editOnKeyDown(editor: DraftEditor, e: SyntheticKeyboardEvent<>): void {
       }
   }
 
-  var command = editor.props.keyBindingFn(e);
+  const command = editor.props.keyBindingFn(e);
 
   // If no command is specified, allow keydown event to continue.
   if (!command) {
@@ -189,7 +189,7 @@ function editOnKeyDown(editor: DraftEditor, e: SyntheticKeyboardEvent<>): void {
     return;
   }
 
-  var newState = onKeyCommand(command, editorState);
+  const newState = onKeyCommand(command, editorState);
   if (newState !== editorState) {
     editor.update(newState);
   }
diff --git a/src/component/handlers/edit/editOnPaste.js b/src/component/handlers/edit/editOnPaste.js
index fad7f09e6b..738788ad59 100644
--- a/src/component/handlers/edit/editOnPaste.js
+++ b/src/component/handlers/edit/editOnPaste.js
@@ -16,30 +16,30 @@ import type {BlockMap} from 'BlockMap';
 import type DraftEditor from 'DraftEditor.react';
 import type {EntityMap} from 'EntityMap';
 
-var BlockMapBuilder = require('BlockMapBuilder');
-var CharacterMetadata = require('CharacterMetadata');
-var DataTransfer = require('DataTransfer');
-var DraftModifier = require('DraftModifier');
-var DraftPasteProcessor = require('DraftPasteProcessor');
-var EditorState = require('EditorState');
-var RichTextEditorUtil = require('RichTextEditorUtil');
-
-var getEntityKeyForSelection = require('getEntityKeyForSelection');
-var getTextContentFromFiles = require('getTextContentFromFiles');
+const BlockMapBuilder = require('BlockMapBuilder');
+const CharacterMetadata = require('CharacterMetadata');
+const DataTransfer = require('DataTransfer');
+const DraftModifier = require('DraftModifier');
+const DraftPasteProcessor = require('DraftPasteProcessor');
+const EditorState = require('EditorState');
+const RichTextEditorUtil = require('RichTextEditorUtil');
+
+const getEntityKeyForSelection = require('getEntityKeyForSelection');
+const getTextContentFromFiles = require('getTextContentFromFiles');
 const isEventHandled = require('isEventHandled');
-var splitTextIntoTextBlocks = require('splitTextIntoTextBlocks');
+const splitTextIntoTextBlocks = require('splitTextIntoTextBlocks');
 
 /**
  * Paste content.
  */
 function editOnPaste(editor: DraftEditor, e: SyntheticClipboardEvent<>): void {
   e.preventDefault();
-  var data = new DataTransfer(e.clipboardData);
+  const data = new DataTransfer(e.clipboardData);
 
   // Get files, unless this is likely to be a string the user wants inline.
   if (!data.isRichText()) {
-    var files = data.getFiles();
-    var defaultFileText = data.getText();
+    const files = data.getFiles();
+    const defaultFileText = data.getText();
     if (files.length > 0) {
       // Allow customized paste handling for images, etc. Otherwise, fall
       // through to insert text contents into the editor.
@@ -56,27 +56,27 @@ function editOnPaste(editor: DraftEditor, e: SyntheticClipboardEvent<>): void {
           return;
         }
 
-        var editorState = editor._latestEditorState;
-        var blocks = splitTextIntoTextBlocks(fileText);
-        var character = CharacterMetadata.create({
+        const editorState = editor._latestEditorState;
+        const blocks = splitTextIntoTextBlocks(fileText);
+        const character = CharacterMetadata.create({
           style: editorState.getCurrentInlineStyle(),
           entity: getEntityKeyForSelection(
             editorState.getCurrentContent(),
             editorState.getSelection(),
           ),
         });
-        var currentBlockType = RichTextEditorUtil.getCurrentBlockType(
+        const currentBlockType = RichTextEditorUtil.getCurrentBlockType(
           editorState,
         );
 
-        var text = DraftPasteProcessor.processText(
+        const text = DraftPasteProcessor.processText(
           blocks,
           character,
           currentBlockType,
         );
-        var fragment = BlockMapBuilder.createFromArray(text);
+        const fragment = BlockMapBuilder.createFromArray(text);
 
-        var withInsertedText = DraftModifier.replaceWithFragment(
+        const withInsertedText = DraftModifier.replaceWithFragment(
           editorState.getCurrentContent(),
           editorState.getSelection(),
           fragment,
@@ -150,14 +150,14 @@ function editOnPaste(editor: DraftEditor, e: SyntheticClipboardEvent<>): void {
 
     // If there is html paste data, try to parse that.
     if (html) {
-      var htmlFragment = DraftPasteProcessor.processHTML(
+      const htmlFragment = DraftPasteProcessor.processHTML(
         html,
         editor.props.blockRenderMap,
       );
       if (htmlFragment) {
         const {contentBlocks, entityMap} = htmlFragment;
         if (contentBlocks) {
-          var htmlMap = BlockMapBuilder.createFromArray(contentBlocks);
+          const htmlMap = BlockMapBuilder.createFromArray(contentBlocks);
           editor.update(
             insertFragment(editor._latestEditorState, htmlMap, entityMap),
           );
@@ -172,7 +172,7 @@ function editOnPaste(editor: DraftEditor, e: SyntheticClipboardEvent<>): void {
   }
 
   if (textBlocks.length) {
-    var character = CharacterMetadata.create({
+    const character = CharacterMetadata.create({
       style: editorState.getCurrentInlineStyle(),
       entity: getEntityKeyForSelection(
         editorState.getCurrentContent(),
@@ -180,15 +180,17 @@ function editOnPaste(editor: DraftEditor, e: SyntheticClipboardEvent<>): void {
       ),
     });
 
-    var currentBlockType = RichTextEditorUtil.getCurrentBlockType(editorState);
+    const currentBlockType = RichTextEditorUtil.getCurrentBlockType(
+      editorState,
+    );
 
-    var textFragment = DraftPasteProcessor.processText(
+    const textFragment = DraftPasteProcessor.processText(
       textBlocks,
       character,
       currentBlockType,
     );
 
-    var textMap = BlockMapBuilder.createFromArray(textFragment);
+    const textMap = BlockMapBuilder.createFromArray(textFragment);
     editor.update(insertFragment(editor._latestEditorState, textMap));
   }
 }
@@ -198,7 +200,7 @@ function insertFragment(
   fragment: BlockMap,
   entityMap: ?EntityMap,
 ): EditorState {
-  var newContent = DraftModifier.replaceWithFragment(
+  const newContent = DraftModifier.replaceWithFragment(
     editorState.getCurrentContent(),
     editorState.getSelection(),
     fragment,
diff --git a/src/component/handlers/edit/editOnSelect.js b/src/component/handlers/edit/editOnSelect.js
index 2187632261..39c957c3ce 100644
--- a/src/component/handlers/edit/editOnSelect.js
+++ b/src/component/handlers/edit/editOnSelect.js
@@ -15,10 +15,10 @@
 import type DraftEditor from 'DraftEditor.react';
 
 const DraftJsDebugLogging = require('DraftJsDebugLogging');
-var EditorState = require('EditorState');
-var ReactDOM = require('ReactDOM');
+const EditorState = require('EditorState');
+const ReactDOM = require('ReactDOM');
 
-var getDraftEditorSelection = require('getDraftEditorSelection');
+const getDraftEditorSelection = require('getDraftEditorSelection');
 const invariant = require('invariant');
 
 function editOnSelect(editor: DraftEditor): void {
@@ -39,18 +39,18 @@ function editOnSelect(editor: DraftEditor): void {
     return;
   }
 
-  var editorState = editor.props.editorState;
+  let editorState = editor.props.editorState;
   const editorNode = ReactDOM.findDOMNode(editor.editorContainer);
   invariant(editorNode, 'Missing editorNode');
   invariant(
     editorNode.firstChild instanceof HTMLElement,
     'editorNode.firstChild is not an HTMLElement',
   );
-  var documentSelection = getDraftEditorSelection(
+  const documentSelection = getDraftEditorSelection(
     editorState,
     editorNode.firstChild,
   );
-  var updatedSelectionState = documentSelection.selectionState;
+  const updatedSelectionState = documentSelection.selectionState;
 
   if (updatedSelectionState !== editorState.getSelection()) {
     if (documentSelection.needsRecovery) {
diff --git a/src/component/handlers/edit/getFragmentFromSelection.js b/src/component/handlers/edit/getFragmentFromSelection.js
index ade367a244..eaeb74aefb 100644
--- a/src/component/handlers/edit/getFragmentFromSelection.js
+++ b/src/component/handlers/edit/getFragmentFromSelection.js
@@ -15,10 +15,10 @@
 import type {BlockMap} from 'BlockMap';
 import type EditorState from 'EditorState';
 
-var getContentStateFragment = require('getContentStateFragment');
+const getContentStateFragment = require('getContentStateFragment');
 
 function getFragmentFromSelection(editorState: EditorState): ?BlockMap {
-  var selectionState = editorState.getSelection();
+  const selectionState = editorState.getSelection();
 
   if (selectionState.isCollapsed()) {
     return null;
diff --git a/src/component/selection/DraftOffsetKey.js b/src/component/selection/DraftOffsetKey.js
index 1e4defc992..76e3746dcd 100644
--- a/src/component/selection/DraftOffsetKey.js
+++ b/src/component/selection/DraftOffsetKey.js
@@ -14,9 +14,9 @@
 
 import type {DraftOffsetKeyPath} from 'DraftOffsetKeyPath';
 
-var KEY_DELIMITER = '-';
+const KEY_DELIMITER = '-';
 
-var DraftOffsetKey = {
+const DraftOffsetKey = {
   encode: function(
     blockKey: string,
     decoratorKey: number,
@@ -26,7 +26,7 @@ var DraftOffsetKey = {
   },
 
   decode: function(offsetKey: string): DraftOffsetKeyPath {
-    var [blockKey, decoratorKey, leafKey] = offsetKey.split(KEY_DELIMITER);
+    const [blockKey, decoratorKey, leafKey] = offsetKey.split(KEY_DELIMITER);
     return {
       blockKey,
       decoratorKey: parseInt(decoratorKey, 10),
diff --git a/src/component/selection/expandRangeToStartOfLine.js b/src/component/selection/expandRangeToStartOfLine.js
index c1898e2a5f..726fcb9c71 100644
--- a/src/component/selection/expandRangeToStartOfLine.js
+++ b/src/component/selection/expandRangeToStartOfLine.js
@@ -10,17 +10,17 @@
  * @flow
  */
 
-var UnicodeUtils = require('UnicodeUtils');
+const UnicodeUtils = require('UnicodeUtils');
 
-var getRangeClientRects = require('getRangeClientRects');
-var invariant = require('invariant');
+const getRangeClientRects = require('getRangeClientRects');
+const invariant = require('invariant');
 
 /**
  * Return the computed line height, in pixels, for the provided element.
  */
 function getLineHeightPx(element: Element): number {
-  var computed = getComputedStyle(element);
-  var div = document.createElement('div');
+  const computed = getComputedStyle(element);
+  const div = document.createElement('div');
   div.style.fontFamily = computed.fontFamily;
   div.style.fontSize = computed.fontSize;
   div.style.fontStyle = computed.fontStyle;
@@ -34,7 +34,7 @@ function getLineHeightPx(element: Element): number {
 
   // forced layout here
   documentBody.appendChild(div);
-  var rect = div.getBoundingClientRect();
+  const rect = div.getBoundingClientRect();
   documentBody.removeChild(div);
 
   return rect.height;
@@ -56,13 +56,13 @@ function areRectsOnOneLine(
   rects: Array<ClientRect>,
   lineHeight: number,
 ): boolean {
-  var minTop = Infinity;
-  var minBottom = Infinity;
-  var maxTop = -Infinity;
-  var maxBottom = -Infinity;
+  let minTop = Infinity;
+  let minBottom = Infinity;
+  let maxTop = -Infinity;
+  let maxBottom = -Infinity;
 
-  for (var ii = 0; ii < rects.length; ii++) {
-    var rect = rects[ii];
+  for (let ii = 0; ii < rects.length; ii++) {
+    const rect = rects[ii];
     if (rect.width === 0 || rect.width === 1) {
       // When a range starts or ends a soft wrap, many browsers (Chrome, IE,
       // Safari) include an empty rect on the previous or next line. When the
@@ -114,11 +114,11 @@ function expandRangeToStartOfLine(range: Range): Range {
   );
   range = range.cloneRange();
 
-  var containingElement = range.startContainer;
+  let containingElement = range.startContainer;
   if (containingElement.nodeType !== 1) {
     containingElement = containingElement.parentNode;
   }
-  var lineHeight = getLineHeightPx((containingElement: any));
+  const lineHeight = getLineHeightPx((containingElement: any));
 
   // Imagine our text looks like:
   //   <div><span>once upon a time, there was a <em>boy
@@ -131,8 +131,8 @@ function expandRangeToStartOfLine(range: Range): Range {
   // the break point is inside the span, then inside the <em>, then in its text
   // node child, the actual break point before "who".
 
-  var bestContainer = range.endContainer;
-  var bestOffset = range.endOffset;
+  let bestContainer = range.endContainer;
+  let bestOffset = range.endOffset;
   range.setStart(range.startContainer, 0);
 
   while (areRectsOnOneLine(getRangeClientRects(range), lineHeight)) {
@@ -161,13 +161,14 @@ function expandRangeToStartOfLine(range: Range): Range {
 
   // At all times, (bestContainer, bestOffset) is the latest single-line start
   // point that we know of.
-  var currentContainer = bestContainer;
-  var maxIndexToConsider = bestOffset - 1;
+  let currentContainer = bestContainer;
+  let maxIndexToConsider = bestOffset - 1;
 
   do {
-    var nodeValue = currentContainer.nodeValue;
+    const nodeValue = currentContainer.nodeValue;
+    let ii = maxIndexToConsider;
 
-    for (var ii = maxIndexToConsider; ii >= 0; ii--) {
+    for (; ii >= 0; ii--) {
       if (
         nodeValue != null &&
         ii > 0 &&
diff --git a/src/component/selection/findAncestorOffsetKey.js b/src/component/selection/findAncestorOffsetKey.js
index ccc2812ae6..befa142820 100644
--- a/src/component/selection/findAncestorOffsetKey.js
+++ b/src/component/selection/findAncestorOffsetKey.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var getSelectionOffsetKeyForNode = require('getSelectionOffsetKeyForNode');
+const getSelectionOffsetKeyForNode = require('getSelectionOffsetKeyForNode');
 
 /**
  * Get the key from the node's nearest offset-aware ancestor.
@@ -20,7 +20,7 @@ var getSelectionOffsetKeyForNode = require('getSelectionOffsetKeyForNode');
 function findAncestorOffsetKey(node: Node): ?string {
   let searchNode = node;
   while (searchNode && searchNode !== document.documentElement) {
-    var key = getSelectionOffsetKeyForNode(searchNode);
+    const key = getSelectionOffsetKeyForNode(searchNode);
     if (key != null) {
       return key;
     }
diff --git a/src/component/selection/getDraftEditorSelection.js b/src/component/selection/getDraftEditorSelection.js
index 6eed3fd793..59df1bb00a 100644
--- a/src/component/selection/getDraftEditorSelection.js
+++ b/src/component/selection/getDraftEditorSelection.js
@@ -15,7 +15,7 @@
 import type {DOMDerivedSelection} from 'DOMDerivedSelection';
 import type EditorState from 'EditorState';
 
-var getDraftEditorSelectionWithNodes = require('getDraftEditorSelectionWithNodes');
+const getDraftEditorSelectionWithNodes = require('getDraftEditorSelectionWithNodes');
 
 /**
  * Convert the current selection range to an anchor/focus pair of offset keys
@@ -25,7 +25,7 @@ function getDraftEditorSelection(
   editorState: EditorState,
   root: HTMLElement,
 ): DOMDerivedSelection {
-  var selection = global.getSelection();
+  const selection = global.getSelection();
 
   // No active selection.
   if (selection.rangeCount === 0) {
diff --git a/src/component/selection/getDraftEditorSelectionWithNodes.js b/src/component/selection/getDraftEditorSelectionWithNodes.js
index 57c64a8b70..cb1f6b1b20 100644
--- a/src/component/selection/getDraftEditorSelectionWithNodes.js
+++ b/src/component/selection/getDraftEditorSelectionWithNodes.js
@@ -15,11 +15,11 @@
 import type {DOMDerivedSelection} from 'DOMDerivedSelection';
 import type EditorState from 'EditorState';
 
-var findAncestorOffsetKey = require('findAncestorOffsetKey');
-var getSelectionOffsetKeyForNode = require('getSelectionOffsetKeyForNode');
-var getUpdatedSelectionState = require('getUpdatedSelectionState');
-var invariant = require('invariant');
-var nullthrows = require('nullthrows');
+const findAncestorOffsetKey = require('findAncestorOffsetKey');
+const getSelectionOffsetKeyForNode = require('getSelectionOffsetKeyForNode');
+const getUpdatedSelectionState = require('getUpdatedSelectionState');
+const invariant = require('invariant');
+const nullthrows = require('nullthrows');
 
 type SelectionPoint = {
   key: string,
@@ -38,8 +38,8 @@ function getDraftEditorSelectionWithNodes(
   focusNode: Node,
   focusOffset: number,
 ): DOMDerivedSelection {
-  var anchorIsTextNode = anchorNode.nodeType === Node.TEXT_NODE;
-  var focusIsTextNode = focusNode.nodeType === Node.TEXT_NODE;
+  const anchorIsTextNode = anchorNode.nodeType === Node.TEXT_NODE;
+  const focusIsTextNode = focusNode.nodeType === Node.TEXT_NODE;
 
   // If the selection range lies only on text nodes, the task is simple.
   // Find the nearest offset-aware elements and use the
@@ -57,9 +57,9 @@ function getDraftEditorSelectionWithNodes(
     };
   }
 
-  var anchorPoint = null;
-  var focusPoint = null;
-  var needsRecovery = true;
+  let anchorPoint = null;
+  let focusPoint = null;
+  let needsRecovery = true;
 
   // An element is selected. Convert this selection range into leaf offset
   // keys and offset values for consumption at the component level. This
@@ -155,7 +155,7 @@ function getPointForNonTextNode(
   childOffset: number,
 ): SelectionPoint {
   let node = startNode;
-  var offsetKey: ?string = findAncestorOffsetKey(node);
+  const offsetKey: ?string = findAncestorOffsetKey(node);
 
   invariant(
     offsetKey != null ||
@@ -181,19 +181,19 @@ function getPointForNonTextNode(
   // find the leftmost ("first") leaf in the tree and use that as the offset
   // key.
   if (childOffset === 0) {
-    var key: ?string = null;
+    let key: ?string = null;
     if (offsetKey != null) {
       key = offsetKey;
     } else {
-      var firstLeaf = getFirstLeaf(node);
+      const firstLeaf = getFirstLeaf(node);
       key = nullthrows(getSelectionOffsetKeyForNode(firstLeaf));
     }
     return {key, offset: 0};
   }
 
-  var nodeBeforeCursor = node.childNodes[childOffset - 1];
-  var leafKey: ?string = null;
-  var textLength: ?number = null;
+  const nodeBeforeCursor = node.childNodes[childOffset - 1];
+  let leafKey: ?string = null;
+  let textLength: ?number = null;
 
   if (!getSelectionOffsetKeyForNode(nodeBeforeCursor)) {
     // Our target node may be a leaf or a text node, in which case we're
@@ -204,7 +204,7 @@ function getPointForNonTextNode(
   } else {
     // Otherwise, we'll look at the child to the left of the cursor and find
     // the last leaf node in its subtree.
-    var lastLeaf = getLastLeaf(nodeBeforeCursor);
+    const lastLeaf = getLastLeaf(nodeBeforeCursor);
     leafKey = nullthrows(getSelectionOffsetKeyForNode(lastLeaf));
     textLength = getTextContentLength(lastLeaf);
   }
@@ -222,7 +222,7 @@ function getPointForNonTextNode(
  * render newlines instead of break tags.
  */
 function getTextContentLength(node: Node): number {
-  var textContent = node.textContent;
+  const textContent = node.textContent;
   return textContent === '\n' ? 0 : textContent.length;
 }
 
diff --git a/src/component/selection/getRangeBoundingClientRect.js b/src/component/selection/getRangeBoundingClientRect.js
index 6c362fef23..55c2d5e88d 100644
--- a/src/component/selection/getRangeBoundingClientRect.js
+++ b/src/component/selection/getRangeBoundingClientRect.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var getRangeClientRects = require('getRangeClientRects');
+const getRangeClientRects = require('getRangeClientRects');
 
 export type FakeClientRect = {
   left: number,
@@ -31,11 +31,11 @@ function getRangeBoundingClientRect(range: Range): FakeClientRect {
   // the first rectangle in list and all of the remaining rectangles of which
   // the height or width is not zero."
   // http://www.w3.org/TR/cssom-view/#dom-range-getboundingclientrect
-  var rects = getRangeClientRects(range);
-  var top = 0;
-  var right = 0;
-  var bottom = 0;
-  var left = 0;
+  const rects = getRangeClientRects(range);
+  let top = 0;
+  let right = 0;
+  let bottom = 0;
+  let left = 0;
 
   if (rects.length) {
     // If the first rectangle has 0 width, we use the second, this is needed
@@ -47,8 +47,8 @@ function getRangeBoundingClientRect(range: Range): FakeClientRect {
       ({top, right, bottom, left} = rects[0]);
     }
 
-    for (var ii = 1; ii < rects.length; ii++) {
-      var rect = rects[ii];
+    for (let ii = 1; ii < rects.length; ii++) {
+      let rect = rects[ii];
       if (rect.height !== 0 && rect.width !== 0) {
         top = Math.min(top, rect.top);
         right = Math.max(right, rect.right);
diff --git a/src/component/selection/getRangeClientRects.js b/src/component/selection/getRangeClientRects.js
index 84b08593e3..d6744815be 100644
--- a/src/component/selection/getRangeClientRects.js
+++ b/src/component/selection/getRangeClientRects.js
@@ -12,11 +12,11 @@
 
 'use strict';
 
-var UserAgent = require('UserAgent');
+const UserAgent = require('UserAgent');
 
-var invariant = require('invariant');
+const invariant = require('invariant');
 
-var isChrome = UserAgent.isBrowser('Chrome');
+const isChrome = UserAgent.isBrowser('Chrome');
 
 // In Chrome, the client rects will include the entire bounds of all nodes that
 // begin (have a start tag) within the selection, even if the selection does
@@ -25,23 +25,23 @@ var isChrome = UserAgent.isBrowser('Chrome');
 // https://code.google.com/p/chromium/issues/detail?id=324437
 /* eslint-disable consistent-return */
 function getRangeClientRectsChrome(range: Range): Array<ClientRect> {
-  var tempRange = range.cloneRange();
-  var clientRects = [];
+  const tempRange = range.cloneRange();
+  const clientRects = [];
 
   for (
-    var ancestor = range.endContainer;
+    let ancestor = range.endContainer;
     ancestor != null;
     ancestor = ancestor.parentNode
   ) {
     // If we've climbed up to the common ancestor, we can now use the
     // original start point and stop climbing the tree.
-    var atCommonAncestor = ancestor === range.commonAncestorContainer;
+    const atCommonAncestor = ancestor === range.commonAncestorContainer;
     if (atCommonAncestor) {
       tempRange.setStart(range.startContainer, range.startOffset);
     } else {
       tempRange.setStart(tempRange.endContainer, 0);
     }
-    var rects = Array.from(tempRange.getClientRects());
+    const rects = Array.from(tempRange.getClientRects());
     clientRects.push(rects);
     if (atCommonAncestor) {
       clientRects.reverse();
@@ -60,7 +60,7 @@ function getRangeClientRectsChrome(range: Range): Array<ClientRect> {
 /**
  * Like range.getClientRects() but normalizes for browser bugs.
  */
-var getRangeClientRects = isChrome
+const getRangeClientRects = isChrome
   ? getRangeClientRectsChrome
   : function(range: Range): Array<ClientRect> {
       return Array.from(range.getClientRects());
diff --git a/src/component/selection/getSampleSelectionMocksForTesting.js b/src/component/selection/getSampleSelectionMocksForTesting.js
index 8d8f90069e..c24f6764bb 100644
--- a/src/component/selection/getSampleSelectionMocksForTesting.js
+++ b/src/component/selection/getSampleSelectionMocksForTesting.js
@@ -6,6 +6,7 @@
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
  *
+ * @format
  */
 
 'use strict';
@@ -15,7 +16,6 @@ const ContentBlock = require('ContentBlock');
 const ContentState = require('ContentState');
 const EditorState = require('EditorState');
 const Immutable = require('immutable');
-
 const {BOLD} = require('SampleDraftInlineStyle');
 const {EMPTY} = CharacterMetadata;
 
diff --git a/src/component/selection/getSampleSelectionMocksForTestingNestedBlocks.js b/src/component/selection/getSampleSelectionMocksForTestingNestedBlocks.js
index 743b69a04a..2f6765c903 100644
--- a/src/component/selection/getSampleSelectionMocksForTestingNestedBlocks.js
+++ b/src/component/selection/getSampleSelectionMocksForTestingNestedBlocks.js
@@ -6,6 +6,7 @@
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
  *
+ * @format
  */
 
 'use strict';
diff --git a/src/component/selection/getSelectionOffsetKeyForNode.js b/src/component/selection/getSelectionOffsetKeyForNode.js
index 04fc6be0bc..a7553138b4 100644
--- a/src/component/selection/getSelectionOffsetKeyForNode.js
+++ b/src/component/selection/getSelectionOffsetKeyForNode.js
@@ -18,12 +18,12 @@
  */
 function getSelectionOffsetKeyForNode(node: Node): ?string {
   if (node instanceof Element) {
-    var offsetKey = node.getAttribute('data-offset-key');
+    const offsetKey = node.getAttribute('data-offset-key');
     if (offsetKey) {
       return offsetKey;
     }
-    for (var ii = 0; ii < node.childNodes.length; ii++) {
-      var childOffsetKey = getSelectionOffsetKeyForNode(node.childNodes[ii]);
+    for (let ii = 0; ii < node.childNodes.length; ii++) {
+      const childOffsetKey = getSelectionOffsetKeyForNode(node.childNodes[ii]);
       if (childOffsetKey) {
         return childOffsetKey;
       }
diff --git a/src/component/selection/getUpdatedSelectionState.js b/src/component/selection/getUpdatedSelectionState.js
index 9f559d538e..9957a08d80 100644
--- a/src/component/selection/getUpdatedSelectionState.js
+++ b/src/component/selection/getUpdatedSelectionState.js
@@ -15,9 +15,9 @@
 import type EditorState from 'EditorState';
 import type SelectionState from 'SelectionState';
 
-var DraftOffsetKey = require('DraftOffsetKey');
+const DraftOffsetKey = require('DraftOffsetKey');
 
-var nullthrows = require('nullthrows');
+const nullthrows = require('nullthrows');
 
 function getUpdatedSelectionState(
   editorState: EditorState,
@@ -26,7 +26,7 @@ function getUpdatedSelectionState(
   focusKey: string,
   focusOffset: number,
 ): SelectionState {
-  var selection: SelectionState = nullthrows(editorState.getSelection());
+  const selection: SelectionState = nullthrows(editorState.getSelection());
   if (__DEV__) {
     if (!anchorKey || !focusKey) {
       /*eslint-disable no-console */
@@ -36,25 +36,25 @@ function getUpdatedSelectionState(
     }
   }
 
-  var anchorPath = DraftOffsetKey.decode(anchorKey);
-  var anchorBlockKey = anchorPath.blockKey;
-  var anchorLeaf = editorState
+  const anchorPath = DraftOffsetKey.decode(anchorKey);
+  const anchorBlockKey = anchorPath.blockKey;
+  const anchorLeaf = editorState
     .getBlockTree(anchorBlockKey)
     .getIn([anchorPath.decoratorKey, 'leaves', anchorPath.leafKey]);
 
-  var focusPath = DraftOffsetKey.decode(focusKey);
-  var focusBlockKey = focusPath.blockKey;
-  var focusLeaf = editorState
+  const focusPath = DraftOffsetKey.decode(focusKey);
+  const focusBlockKey = focusPath.blockKey;
+  const focusLeaf = editorState
     .getBlockTree(focusBlockKey)
     .getIn([focusPath.decoratorKey, 'leaves', focusPath.leafKey]);
 
-  var anchorLeafStart: number = anchorLeaf.get('start');
-  var focusLeafStart: number = focusLeaf.get('start');
+  const anchorLeafStart: number = anchorLeaf.get('start');
+  const focusLeafStart: number = focusLeaf.get('start');
 
-  var anchorBlockOffset = anchorLeaf ? anchorLeafStart + anchorOffset : null;
-  var focusBlockOffset = focusLeaf ? focusLeafStart + focusOffset : null;
+  const anchorBlockOffset = anchorLeaf ? anchorLeafStart + anchorOffset : null;
+  const focusBlockOffset = focusLeaf ? focusLeafStart + focusOffset : null;
 
-  var areEqual =
+  const areEqual =
     selection.getAnchorKey() === anchorBlockKey &&
     selection.getAnchorOffset() === anchorBlockOffset &&
     selection.getFocusKey() === focusBlockKey &&
@@ -64,17 +64,17 @@ function getUpdatedSelectionState(
     return selection;
   }
 
-  var isBackward = false;
+  let isBackward = false;
   if (anchorBlockKey === focusBlockKey) {
-    var anchorLeafEnd: number = anchorLeaf.get('end');
-    var focusLeafEnd: number = focusLeaf.get('end');
+    const anchorLeafEnd: number = anchorLeaf.get('end');
+    const focusLeafEnd: number = focusLeaf.get('end');
     if (focusLeafStart === anchorLeafStart && focusLeafEnd === anchorLeafEnd) {
       isBackward = focusOffset < anchorOffset;
     } else {
       isBackward = focusLeafStart < anchorLeafStart;
     }
   } else {
-    var startKey = editorState
+    const startKey = editorState
       .getCurrentContent()
       .getBlockMap()
       .keySeq()
diff --git a/src/component/selection/isSelectionAtLeafStart.js b/src/component/selection/isSelectionAtLeafStart.js
index 78e3bb035f..5325155a6e 100644
--- a/src/component/selection/isSelectionAtLeafStart.js
+++ b/src/component/selection/isSelectionAtLeafStart.js
@@ -15,12 +15,12 @@
 import type EditorState from 'EditorState';
 
 function isSelectionAtLeafStart(editorState: EditorState): boolean {
-  var selection = editorState.getSelection();
-  var anchorKey = selection.getAnchorKey();
-  var blockTree = editorState.getBlockTree(anchorKey);
-  var offset = selection.getStartOffset();
+  const selection = editorState.getSelection();
+  const anchorKey = selection.getAnchorKey();
+  const blockTree = editorState.getBlockTree(anchorKey);
+  const offset = selection.getStartOffset();
 
-  var isAtStart = false;
+  let isAtStart = false;
 
   blockTree.some(leafSet => {
     if (offset === leafSet.get('start')) {
@@ -30,7 +30,7 @@ function isSelectionAtLeafStart(editorState: EditorState): boolean {
 
     if (offset < leafSet.get('end')) {
       return leafSet.get('leaves').some(leaf => {
-        var leafStart = leaf.get('start');
+        const leafStart = leaf.get('start');
         if (offset === leafStart) {
           isAtStart = true;
           return true;
diff --git a/src/component/selection/setDraftEditorSelection.js b/src/component/selection/setDraftEditorSelection.js
index d260cc943c..0308210f57 100644
--- a/src/component/selection/setDraftEditorSelection.js
+++ b/src/component/selection/setDraftEditorSelection.js
@@ -28,7 +28,7 @@ function getAnonymizedDOM(
     return '[empty]';
   }
 
-  var anonymized = anonymizeTextWithin(node, getNodeLabels);
+  const anonymized = anonymizeTextWithin(node, getNodeLabels);
   if (anonymized.nodeType === Node.TEXT_NODE) {
     return anonymized.textContent;
   }
@@ -47,7 +47,7 @@ function anonymizeTextWithin(
   const labels = getNodeLabels !== undefined ? getNodeLabels(node) : [];
 
   if (node.nodeType === Node.TEXT_NODE) {
-    var length = node.textContent.length;
+    const length = node.textContent.length;
     return document.createTextNode(
       '[text ' +
         length +
@@ -56,12 +56,12 @@ function anonymizeTextWithin(
     );
   }
 
-  var clone = node.cloneNode();
+  const clone = node.cloneNode();
   if (clone.nodeType === 1 && labels.length) {
     ((clone: any): Element).setAttribute('data-labels', labels.join(', '));
   }
-  var childNodes = node.childNodes;
-  for (var ii = 0; ii < childNodes.length; ii++) {
+  const childNodes = node.childNodes;
+  for (let ii = 0; ii < childNodes.length; ii++) {
     clone.appendChild(anonymizeTextWithin(childNodes[ii], getNodeLabels));
   }
 
@@ -117,17 +117,17 @@ function setDraftEditorSelection(
     return;
   }
 
-  var selection = global.getSelection();
-  var anchorKey = selectionState.getAnchorKey();
-  var anchorOffset = selectionState.getAnchorOffset();
-  var focusKey = selectionState.getFocusKey();
-  var focusOffset = selectionState.getFocusOffset();
-  var isBackward = selectionState.getIsBackward();
+  const selection = global.getSelection();
+  let anchorKey = selectionState.getAnchorKey();
+  let anchorOffset = selectionState.getAnchorOffset();
+  let focusKey = selectionState.getFocusKey();
+  let focusOffset = selectionState.getFocusOffset();
+  let isBackward = selectionState.getIsBackward();
 
   // IE doesn't support backward selection. Swap key/offset pairs.
   if (!selection.extend && isBackward) {
-    var tempKey = anchorKey;
-    var tempOffset = anchorOffset;
+    const tempKey = anchorKey;
+    const tempOffset = anchorOffset;
     anchorKey = focusKey;
     anchorOffset = focusOffset;
     focusKey = tempKey;
@@ -135,12 +135,12 @@ function setDraftEditorSelection(
     isBackward = false;
   }
 
-  var hasAnchor =
+  const hasAnchor =
     anchorKey === blockKey &&
     nodeStart <= anchorOffset &&
     nodeEnd >= anchorOffset;
 
-  var hasFocus =
+  const hasFocus =
     focusKey === blockKey && nodeStart <= focusOffset && nodeEnd >= focusOffset;
 
   // If the selection is entirely bound within this node, set the selection
@@ -204,8 +204,8 @@ function setDraftEditorSelection(
     // We keep track of it, reset the selection range, and extend it
     // back to the focus point.
     if (hasAnchor) {
-      var storedFocusNode = selection.focusNode;
-      var storedFocusOffset = selection.focusOffset;
+      const storedFocusNode = selection.focusNode;
+      const storedFocusOffset = selection.focusOffset;
 
       selection.removeAllRanges();
       addPointToSelection(
@@ -302,7 +302,7 @@ function addFocusToSelection(
     // Additionally, clone the selection range. IE11 throws an
     // InvalidStateError when attempting to access selection properties
     // after the range is detached.
-    var range = selection.getRangeAt(0);
+    const range = selection.getRangeAt(0);
     range.setEnd(node, offset);
     selection.addRange(range.cloneRange());
   }
@@ -314,7 +314,7 @@ function addPointToSelection(
   offset: number,
   selectionState: SelectionState,
 ): void {
-  var range = document.createRange();
+  const range = document.createRange();
   // logging to catch bug that is being reported in t16250795
   if (offset > getNodeLength(node)) {
     // in this case we know that the call to 'range.setStart' is about to throw
diff --git a/src/component/utils/KeyBindingUtil.js b/src/component/utils/KeyBindingUtil.js
index 07889a6cc6..4eb8ca5fb9 100644
--- a/src/component/utils/KeyBindingUtil.js
+++ b/src/component/utils/KeyBindingUtil.js
@@ -12,11 +12,11 @@
 
 'use strict';
 
-var UserAgent = require('UserAgent');
+const UserAgent = require('UserAgent');
 
-var isOSX = UserAgent.isPlatform('Mac OS X');
+const isOSX = UserAgent.isPlatform('Mac OS X');
 
-var KeyBindingUtil = {
+const KeyBindingUtil = {
   /**
    * Check whether the ctrlKey modifier is *not* being used in conjunction with
    * the altKey modifier. If they are combined, the result is an `altGraph`
diff --git a/src/component/utils/getDefaultKeyBinding.js b/src/component/utils/getDefaultKeyBinding.js
index 874d4b5a2f..0c84b3f5eb 100644
--- a/src/component/utils/getDefaultKeyBinding.js
+++ b/src/component/utils/getDefaultKeyBinding.js
@@ -14,18 +14,18 @@
 
 import type {DraftEditorCommand} from 'DraftEditorCommand';
 
-var KeyBindingUtil = require('KeyBindingUtil');
-var Keys = require('Keys');
-var UserAgent = require('UserAgent');
+const KeyBindingUtil = require('KeyBindingUtil');
+const Keys = require('Keys');
+const UserAgent = require('UserAgent');
 
-var isOSX = UserAgent.isPlatform('Mac OS X');
+const isOSX = UserAgent.isPlatform('Mac OS X');
 
 // Firefox on OSX had a bug resulting in navigation instead of cursor movement.
 // This bug was fixed in Firefox 29. Feature detection is virtually impossible
 // so we just check the version number. See #342765.
-var shouldFixFirefoxMovement = isOSX && UserAgent.isBrowser('Firefox < 29');
+const shouldFixFirefoxMovement = isOSX && UserAgent.isBrowser('Firefox < 29');
 
-var {hasCommandModifier, isCtrlKeyCommand} = KeyBindingUtil;
+const {hasCommandModifier, isCtrlKeyCommand} = KeyBindingUtil;
 
 function shouldRemoveWord(e: SyntheticKeyboardEvent<>): boolean {
   return (isOSX && e.altKey) || isCtrlKeyCommand(e);
diff --git a/src/component/utils/getTextContentFromFiles.js b/src/component/utils/getTextContentFromFiles.js
index c4b1f4e38d..582f83e6c9 100644
--- a/src/component/utils/getTextContentFromFiles.js
+++ b/src/component/utils/getTextContentFromFiles.js
@@ -14,16 +14,16 @@
 
 const invariant = require('invariant');
 
-var TEXT_CLIPPING_REGEX = /\.textClipping$/;
+const TEXT_CLIPPING_REGEX = /\.textClipping$/;
 
-var TEXT_TYPES = {
+const TEXT_TYPES = {
   'text/plain': true,
   'text/html': true,
   'text/rtf': true,
 };
 
 // Somewhat arbitrary upper bound on text size. Let's not lock up the browser.
-var TEXT_SIZE_UPPER_BOUND = 5000;
+const TEXT_SIZE_UPPER_BOUND = 5000;
 
 /**
  * Extract the text content from a file list.
@@ -32,8 +32,8 @@ function getTextContentFromFiles(
   files: Array<File>,
   callback: (contents: string) => void,
 ): void {
-  var readCount = 0;
-  var results = [];
+  let readCount = 0;
+  const results = [];
   files.forEach(function(/*blob*/ file) {
     readFile(file, function(/*string*/ text) {
       readCount++;
@@ -55,7 +55,7 @@ function readFile(file: File, callback: (contents: string) => void): void {
   }
 
   if (file.type === '') {
-    var contents = '';
+    let contents = '';
     // Special-case text clippings, which have an empty type but include
     // `.textClipping` in the file name. `readAsText` results in an empty
     // string for text clippings, so we force the file name to serve
@@ -67,7 +67,7 @@ function readFile(file: File, callback: (contents: string) => void): void {
     return;
   }
 
-  var reader = new FileReader();
+  const reader = new FileReader();
   reader.onload = function() {
     const result = reader.result;
     invariant(
diff --git a/src/component/utils/isSoftNewlineEvent.js b/src/component/utils/isSoftNewlineEvent.js
index 8337804532..af7433a288 100644
--- a/src/component/utils/isSoftNewlineEvent.js
+++ b/src/component/utils/isSoftNewlineEvent.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var Keys = require('Keys');
+const Keys = require('Keys');
 
 function isSoftNewlineEvent(e: SyntheticKeyboardEvent<>): boolean {
   return (
diff --git a/src/component/utils/splitTextIntoTextBlocks.js b/src/component/utils/splitTextIntoTextBlocks.js
index 7cb6b3c7da..24ca0f697a 100644
--- a/src/component/utils/splitTextIntoTextBlocks.js
+++ b/src/component/utils/splitTextIntoTextBlocks.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var NEWLINE_REGEX = /\r\n?|\n/g;
+const NEWLINE_REGEX = /\r\n?|\n/g;
 
 function splitTextIntoTextBlocks(text: string): Array<string> {
   return text.split(NEWLINE_REGEX);
diff --git a/src/model/decorators/CompositeDraftDecorator.js b/src/model/decorators/CompositeDraftDecorator.js
index dcecc8fdbc..3376116223 100644
--- a/src/model/decorators/CompositeDraftDecorator.js
+++ b/src/model/decorators/CompositeDraftDecorator.js
@@ -16,11 +16,11 @@ import type {BlockNodeRecord} from 'BlockNodeRecord';
 import type ContentState from 'ContentState';
 import type {DraftDecorator} from 'DraftDecorator';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var {List} = Immutable;
+const {List} = Immutable;
 
-var DELIMITER = '.';
+const DELIMITER = '.';
 
 /**
  * A CompositeDraftDecorator traverses through a list of DraftDecorator
@@ -55,12 +55,12 @@ class CompositeDraftDecorator {
     block: BlockNodeRecord,
     contentState: ContentState,
   ): List<?string> {
-    var decorations = Array(block.getText().length).fill(null);
+    const decorations = Array(block.getText().length).fill(null);
 
     this._decorators.forEach((/*object*/ decorator, /*number*/ ii) => {
-      var counter = 0;
-      var strategy = decorator.strategy;
-      var callback = (/*number*/ start, /*number*/ end) => {
+      let counter = 0;
+      const strategy = decorator.strategy;
+      const callback = (/*number*/ start, /*number*/ end) => {
         // Find out if any of our matching range is already occupied
         // by another decorator. If so, discard the match. Otherwise, store
         // the component key for rendering.
@@ -76,12 +76,12 @@ class CompositeDraftDecorator {
   }
 
   getComponentForKey(key: string): Function {
-    var componentKey = parseInt(key.split(DELIMITER)[0], 10);
+    const componentKey = parseInt(key.split(DELIMITER)[0], 10);
     return this._decorators[componentKey].component;
   }
 
   getPropsForKey(key: string): ?Object {
-    var componentKey = parseInt(key.split(DELIMITER)[0], 10);
+    const componentKey = parseInt(key.split(DELIMITER)[0], 10);
     return this._decorators[componentKey].props;
   }
 }
@@ -95,7 +95,7 @@ function canOccupySlice(
   start: number,
   end: number,
 ): boolean {
-  for (var ii = start; ii < end; ii++) {
+  for (let ii = start; ii < end; ii++) {
     if (decorations[ii] != null) {
       return false;
     }
@@ -113,7 +113,7 @@ function occupySlice(
   end: number,
   componentKey: string,
 ): void {
-  for (var ii = start; ii < end; ii++) {
+  for (let ii = start; ii < end; ii++) {
     targetArr[ii] = componentKey;
   }
 }
diff --git a/src/model/encoding/DraftStringKey.js b/src/model/encoding/DraftStringKey.js
index f45b655ecf..8f35514ae2 100644
--- a/src/model/encoding/DraftStringKey.js
+++ b/src/model/encoding/DraftStringKey.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var DraftStringKey = {
+const DraftStringKey = {
   stringify: function(key: mixed): string {
     return '_' + String(key);
   },
diff --git a/src/model/encoding/createCharacterList.js b/src/model/encoding/createCharacterList.js
index ea5e7d2bf8..2723bfc570 100644
--- a/src/model/encoding/createCharacterList.js
+++ b/src/model/encoding/createCharacterList.js
@@ -14,17 +14,17 @@
 
 import type {DraftInlineStyle} from 'DraftInlineStyle';
 
-var CharacterMetadata = require('CharacterMetadata');
-var Immutable = require('immutable');
+const CharacterMetadata = require('CharacterMetadata');
+const Immutable = require('immutable');
 
-var {List} = Immutable;
+const {List} = Immutable;
 
 function createCharacterList(
   inlineStyles: Array<DraftInlineStyle>,
   entities: Array<?string>,
 ): List<CharacterMetadata> {
-  var characterArray = inlineStyles.map((style, ii) => {
-    var entity = entities[ii];
+  const characterArray = inlineStyles.map((style, ii) => {
+    const entity = entities[ii];
     return CharacterMetadata.create({style, entity});
   });
   return List(characterArray);
diff --git a/src/model/encoding/decodeEntityRanges.js b/src/model/encoding/decodeEntityRanges.js
index 13380436d4..7260136c26 100644
--- a/src/model/encoding/decodeEntityRanges.js
+++ b/src/model/encoding/decodeEntityRanges.js
@@ -12,9 +12,9 @@
 
 'use strict';
 
-var UnicodeUtils = require('UnicodeUtils');
+const UnicodeUtils = require('UnicodeUtils');
 
-var {substr} = UnicodeUtils;
+const {substr} = UnicodeUtils;
 
 /**
  * Convert to native JavaScript string lengths to determine ranges.
@@ -23,14 +23,14 @@ function decodeEntityRanges(
   text: string,
   ranges: Array<Object>,
 ): Array<?string> {
-  var entities = Array(text.length).fill(null);
+  const entities = Array(text.length).fill(null);
   if (ranges) {
     ranges.forEach(range => {
       // Using Unicode-enabled substrings converted to JavaScript lengths,
       // fill the output array with entity keys.
-      var start = substr(text, 0, range.offset).length;
-      var end = start + substr(text, range.offset, range.length).length;
-      for (var ii = start; ii < end; ii++) {
+      const start = substr(text, 0, range.offset).length;
+      const end = start + substr(text, range.offset, range.length).length;
+      for (let ii = start; ii < end; ii++) {
         entities[ii] = range.key;
       }
     });
diff --git a/src/model/encoding/decodeInlineStyleRanges.js b/src/model/encoding/decodeInlineStyleRanges.js
index 55d5eedc7e..86bacf247b 100644
--- a/src/model/encoding/decodeInlineStyleRanges.js
+++ b/src/model/encoding/decodeInlineStyleRanges.js
@@ -12,10 +12,10 @@
 
 'use strict';
 
-var {OrderedSet} = require('immutable');
-var UnicodeUtils = require('UnicodeUtils');
+const {OrderedSet} = require('immutable');
+const UnicodeUtils = require('UnicodeUtils');
 
-var {substr} = UnicodeUtils;
+const {substr} = UnicodeUtils;
 
 import type {DraftInlineStyle} from 'DraftInlineStyle';
 
@@ -28,11 +28,11 @@ function decodeInlineStyleRanges(
   text: string,
   ranges?: Array<Object>,
 ): Array<DraftInlineStyle> {
-  var styles = Array(text.length).fill(EMPTY_SET);
+  const styles = Array(text.length).fill(EMPTY_SET);
   if (ranges) {
     ranges.forEach((/*object*/ range) => {
-      var cursor = substr(text, 0, range.offset).length;
-      var end = cursor + substr(text, range.offset, range.length).length;
+      let cursor = substr(text, 0, range.offset).length;
+      const end = cursor + substr(text, range.offset, range.length).length;
       while (cursor < end) {
         styles[cursor] = styles[cursor].add(range.style);
         cursor++;
diff --git a/src/model/encoding/encodeEntityRanges.js b/src/model/encoding/encodeEntityRanges.js
index 9e07f5a631..61e4fa4d2c 100644
--- a/src/model/encoding/encodeEntityRanges.js
+++ b/src/model/encoding/encodeEntityRanges.js
@@ -15,10 +15,10 @@
 import type {BlockNodeRecord} from 'BlockNodeRecord';
 import type {EntityRange} from 'EntityRange';
 
-var DraftStringKey = require('DraftStringKey');
-var UnicodeUtils = require('UnicodeUtils');
+const DraftStringKey = require('DraftStringKey');
+const UnicodeUtils = require('UnicodeUtils');
 
-var {strlen} = UnicodeUtils;
+const {strlen} = UnicodeUtils;
 
 /**
  * Convert to UTF-8 character counts for storage.
@@ -27,12 +27,12 @@ function encodeEntityRanges(
   block: BlockNodeRecord,
   storageMap: Object,
 ): Array<EntityRange> {
-  var encoded = [];
+  const encoded = [];
   block.findEntityRanges(
     character => !!character.getEntity(),
     (/*number*/ start, /*number*/ end) => {
-      var text = block.getText();
-      var key = block.getEntityAt(start);
+      const text = block.getText();
+      const key = block.getEntityAt(start);
       encoded.push({
         offset: strlen(text.slice(0, start)),
         length: strlen(text.slice(start, end)),
diff --git a/src/model/encoding/encodeInlineStyleRanges.js b/src/model/encoding/encodeInlineStyleRanges.js
index 5f839d011f..8b1e632b39 100644
--- a/src/model/encoding/encodeInlineStyleRanges.js
+++ b/src/model/encoding/encodeInlineStyleRanges.js
@@ -17,13 +17,13 @@ import type {DraftInlineStyle} from 'DraftInlineStyle';
 import type {InlineStyleRange} from 'InlineStyleRange';
 import type {List} from 'immutable';
 
-var UnicodeUtils = require('UnicodeUtils');
+const UnicodeUtils = require('UnicodeUtils');
 
-var findRangesImmutable = require('findRangesImmutable');
+const findRangesImmutable = require('findRangesImmutable');
 
-var areEqual = (a, b) => a === b;
-var isTruthy = a => !!a;
-var EMPTY_ARRAY = [];
+const areEqual = (a, b) => a === b;
+const isTruthy = a => !!a;
+const EMPTY_ARRAY = [];
 
 /**
  * Helper function for getting encoded styles for each inline style. Convert
@@ -34,10 +34,10 @@ function getEncodedInlinesForType(
   styleList: List<DraftInlineStyle>,
   styleToEncode: string,
 ): Array<InlineStyleRange> {
-  var ranges = [];
+  const ranges = [];
 
   // Obtain an array with ranges for only the specified style.
-  var filteredInlines = styleList
+  const filteredInlines = styleList
     .map(style => style.has(styleToEncode))
     .toList();
 
@@ -47,7 +47,7 @@ function getEncodedInlinesForType(
     // We only want to keep ranges with nonzero style values.
     isTruthy,
     (start, end) => {
-      var text = block.getText();
+      const text = block.getText();
       ranges.push({
         offset: UnicodeUtils.strlen(text.slice(0, start)),
         length: UnicodeUtils.strlen(text.slice(start, end)),
@@ -66,11 +66,11 @@ function getEncodedInlinesForType(
 function encodeInlineStyleRanges(
   block: BlockNodeRecord,
 ): Array<InlineStyleRange> {
-  var styleList = block
+  const styleList = block
     .getCharacterList()
     .map(c => c.getStyle())
     .toList();
-  var ranges = styleList
+  const ranges = styleList
     .flatten()
     .toSet()
     .map(style => getEncodedInlinesForType(block, styleList, style));
diff --git a/src/model/encoding/sanitizeDraftText.js b/src/model/encoding/sanitizeDraftText.js
index 82eb5304ea..8527c5f5fa 100644
--- a/src/model/encoding/sanitizeDraftText.js
+++ b/src/model/encoding/sanitizeDraftText.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var REGEX_BLOCK_DELIMITER = new RegExp('\r', 'g');
+const REGEX_BLOCK_DELIMITER = new RegExp('\r', 'g');
 
 function sanitizeDraftText(input: string): string {
   return input.replace(REGEX_BLOCK_DELIMITER, '');
diff --git a/src/model/entity/DraftEntity.js b/src/model/entity/DraftEntity.js
index eae088afbb..f2b13e89c3 100644
--- a/src/model/entity/DraftEntity.js
+++ b/src/model/entity/DraftEntity.js
@@ -13,15 +13,15 @@
 import type {DraftEntityMutability} from 'DraftEntityMutability';
 import type {DraftEntityType} from 'DraftEntityType';
 
-var DraftEntityInstance = require('DraftEntityInstance');
-var Immutable = require('immutable');
+const DraftEntityInstance = require('DraftEntityInstance');
+const Immutable = require('immutable');
 
-var invariant = require('invariant');
+const invariant = require('invariant');
 
-var {Map} = Immutable;
+const {Map} = Immutable;
 
-var instances: Map<string, DraftEntityInstance> = Map();
-var instanceKey = 0;
+let instances: Map<string, DraftEntityInstance> = Map();
+let instanceKey = 0;
 
 /**
  * Temporary utility for generating the warnings
@@ -95,7 +95,7 @@ export type DraftEntityMapObject = {
  * generated via DraftEntity.create() and used to obtain entity metadata
  * via DraftEntity.get().
  */
-var DraftEntity: DraftEntityMapObject = {
+const DraftEntity: DraftEntityMapObject = {
   /**
    * WARNING: This method will be deprecated soon!
    * Please use 'contentState.getLastCreatedEntityKey' instead.
@@ -219,7 +219,7 @@ var DraftEntity: DraftEntityMapObject = {
    * useful when restoring instances from the server.
    */
   __add: function(instance: DraftEntityInstance): string {
-    var key = '' + ++instanceKey;
+    const key = '' + ++instanceKey;
     instances = instances.set(key, instance);
     return key;
   },
@@ -228,7 +228,7 @@ var DraftEntity: DraftEntityMapObject = {
    * Retrieve the entity corresponding to the supplied key string.
    */
   __get: function(key: string): DraftEntityInstance {
-    var instance = instances.get(key);
+    const instance = instances.get(key);
     invariant(!!instance, 'Unknown DraftEntity key: %s.', key);
     return instance;
   },
@@ -242,9 +242,9 @@ var DraftEntity: DraftEntityMapObject = {
     key: string,
     toMerge: {[key: string]: any},
   ): DraftEntityInstance {
-    var instance = DraftEntity.__get(key);
-    var newData = {...instance.getData(), ...toMerge};
-    var newInstance = instance.set('data', newData);
+    const instance = DraftEntity.__get(key);
+    const newData = {...instance.getData(), ...toMerge};
+    const newInstance = instance.set('data', newData);
     instances = instances.set(key, newInstance);
     return newInstance;
   },
diff --git a/src/model/entity/DraftEntityInstance.js b/src/model/entity/DraftEntityInstance.js
index 4d38a289ba..e79b111e35 100644
--- a/src/model/entity/DraftEntityInstance.js
+++ b/src/model/entity/DraftEntityInstance.js
@@ -16,11 +16,11 @@
 import type {DraftEntityMutability} from 'DraftEntityMutability';
 import type {DraftEntityType} from 'DraftEntityType';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var {Record} = Immutable;
+const {Record} = Immutable;
 
-var DraftEntityInstanceRecord = Record({
+const DraftEntityInstanceRecord = Record({
   type: 'TOKEN',
   mutability: 'IMMUTABLE',
   data: Object,
diff --git a/src/model/entity/DraftEntityMutability.js b/src/model/entity/DraftEntityMutability.js
index 92507029af..e334f3cba0 100644
--- a/src/model/entity/DraftEntityMutability.js
+++ b/src/model/entity/DraftEntityMutability.js
@@ -12,7 +12,7 @@
 
 'use strict';
 
-var ComposedEntityMutability = require('ComposedEntityMutability');
+const ComposedEntityMutability = require('ComposedEntityMutability');
 
 /**
  * An enum representing the possible "mutability" options for an entity.
diff --git a/src/model/entity/__mocks__/DraftEntity.js b/src/model/entity/__mocks__/DraftEntity.js
index ec7d0022fa..a233a4b8d3 100644
--- a/src/model/entity/__mocks__/DraftEntity.js
+++ b/src/model/entity/__mocks__/DraftEntity.js
@@ -9,15 +9,15 @@
  * @format
  */
 
-var DraftEntity = jest.genMockFromModule('DraftEntity');
+const DraftEntity = jest.genMockFromModule('DraftEntity');
 
-var DraftEntityInstance = {
+const DraftEntityInstance = {
   getType: jest.fn(() => ''),
   getMutability: jest.fn(() => ''),
   getData: jest.fn(() => ({})),
 };
 
-var count = 0;
+let count = 0;
 
 DraftEntity.create = jest.fn(function() {
   count++;
diff --git a/src/model/entity/getEntityKeyForSelection.js b/src/model/entity/getEntityKeyForSelection.js
index 7c8378945a..1fa85f8277 100644
--- a/src/model/entity/getEntityKeyForSelection.js
+++ b/src/model/entity/getEntityKeyForSelection.js
@@ -25,11 +25,11 @@ function getEntityKeyForSelection(
   contentState: ContentState,
   targetSelection: SelectionState,
 ): ?string {
-  var entityKey;
+  let entityKey;
 
   if (targetSelection.isCollapsed()) {
-    var key = targetSelection.getAnchorKey();
-    var offset = targetSelection.getAnchorOffset();
+    const key = targetSelection.getAnchorKey();
+    const offset = targetSelection.getAnchorOffset();
     if (offset > 0) {
       entityKey = contentState.getBlockForKey(key).getEntityAt(offset - 1);
       if (entityKey !== contentState.getBlockForKey(key).getEntityAt(offset)) {
@@ -40,9 +40,9 @@ function getEntityKeyForSelection(
     return null;
   }
 
-  var startKey = targetSelection.getStartKey();
-  var startOffset = targetSelection.getStartOffset();
-  var startBlock = contentState.getBlockForKey(startKey);
+  const startKey = targetSelection.getStartKey();
+  const startOffset = targetSelection.getStartOffset();
+  const startBlock = contentState.getBlockForKey(startKey);
 
   entityKey =
     startOffset === startBlock.getLength()
@@ -58,7 +58,7 @@ function getEntityKeyForSelection(
  */
 function filterKey(entityMap: EntityMap, entityKey: ?string): ?string {
   if (entityKey) {
-    var entity = entityMap.__get(entityKey);
+    const entity = entityMap.__get(entityKey);
     return entity.getMutability() === 'MUTABLE' ? entityKey : null;
   }
   return null;
diff --git a/src/model/entity/getTextAfterNearestEntity.js b/src/model/entity/getTextAfterNearestEntity.js
index 104b3f77ca..d16aec2474 100644
--- a/src/model/entity/getTextAfterNearestEntity.js
+++ b/src/model/entity/getTextAfterNearestEntity.js
@@ -22,7 +22,7 @@ function getTextAfterNearestEntity(
   block: BlockNodeRecord,
   offset: number,
 ): string {
-  var start = offset;
+  let start = offset;
 
   // Get start based on where the last entity ended.
   while (start > 0 && block.getEntityAt(start - 1) === null) {
diff --git a/src/model/immutable/BlockMapBuilder.js b/src/model/immutable/BlockMapBuilder.js
index b79f39f5af..f4bbf1f3cf 100644
--- a/src/model/immutable/BlockMapBuilder.js
+++ b/src/model/immutable/BlockMapBuilder.js
@@ -15,11 +15,11 @@
 import type {BlockMap} from 'BlockMap';
 import type {BlockNodeRecord} from 'BlockNodeRecord';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var {OrderedMap} = Immutable;
+const {OrderedMap} = Immutable;
 
-var BlockMapBuilder = {
+const BlockMapBuilder = {
   createFromArray: function(blocks: Array<BlockNodeRecord>): BlockMap {
     return OrderedMap(blocks.map(block => [block.getKey(), block]));
   },
diff --git a/src/model/immutable/BlockTree.js b/src/model/immutable/BlockTree.js
index 097c4c01af..5caaf8d6e4 100644
--- a/src/model/immutable/BlockTree.js
+++ b/src/model/immutable/BlockTree.js
@@ -17,18 +17,18 @@ import type CharacterMetadata from 'CharacterMetadata';
 import type ContentState from 'ContentState';
 import type {DraftDecoratorType} from 'DraftDecoratorType';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var emptyFunction = require('emptyFunction');
-var findRangesImmutable = require('findRangesImmutable');
+const emptyFunction = require('emptyFunction');
+const findRangesImmutable = require('findRangesImmutable');
 
-var {List, Repeat, Record} = Immutable;
+const {List, Repeat, Record} = Immutable;
 
-var returnTrue = emptyFunction.thatReturnsTrue;
+const returnTrue = emptyFunction.thatReturnsTrue;
 
-var FINGERPRINT_DELIMITER = '-';
+const FINGERPRINT_DELIMITER = '-';
 
-var defaultLeafRange: {
+const defaultLeafRange: {
   start: ?number,
   end: ?number,
 } = {
@@ -36,9 +36,9 @@ var defaultLeafRange: {
   end: null,
 };
 
-var LeafRange = Record(defaultLeafRange);
+const LeafRange = Record(defaultLeafRange);
 
-var defaultDecoratorRange: {
+const defaultDecoratorRange: {
   start: ?number,
   end: ?number,
   decoratorKey: ?string,
@@ -50,9 +50,9 @@ var defaultDecoratorRange: {
   leaves: null,
 };
 
-var DecoratorRange = Record(defaultDecoratorRange);
+const DecoratorRange = Record(defaultDecoratorRange);
 
-var BlockTree = {
+const BlockTree = {
   /**
    * Generate a block tree for a given ContentBlock/decorator pair.
    */
@@ -61,7 +61,7 @@ var BlockTree = {
     block: BlockNodeRecord,
     decorator: ?DraftDecoratorType,
   ): List<DecoratorRange> {
-    var textLength = block.getLength();
+    const textLength = block.getLength();
     if (!textLength) {
       return List.of(
         new DecoratorRange({
@@ -73,12 +73,12 @@ var BlockTree = {
       );
     }
 
-    var leafSets = [];
-    var decorations = decorator
+    const leafSets = [];
+    const decorations = decorator
       ? decorator.getDecorations(block, contentState)
       : List(Repeat(null, textLength));
 
-    var chars = block.getCharacterList();
+    const chars = block.getCharacterList();
 
     findRangesImmutable(decorations, areEqual, returnTrue, (start, end) => {
       leafSets.push(
@@ -102,8 +102,8 @@ var BlockTree = {
   getFingerprint: function(tree: List<DecoratorRange>): string {
     return tree
       .map(leafSet => {
-        var decoratorKey = leafSet.get('decoratorKey');
-        var fingerprintString =
+        const decoratorKey = leafSet.get('decoratorKey');
+        const fingerprintString =
           decoratorKey !== null
             ? decoratorKey + '.' + (leafSet.get('end') - leafSet.get('start'))
             : '';
@@ -120,8 +120,8 @@ function generateLeaves(
   characters: List<CharacterMetadata>,
   offset: number,
 ): List<LeafRange> {
-  var leaves = [];
-  var inlineStyles = characters.map(c => c.getStyle()).toList();
+  const leaves = [];
+  const inlineStyles = characters.map(c => c.getStyle()).toList();
   findRangesImmutable(inlineStyles, areEqual, returnTrue, (start, end) => {
     leaves.push(
       new LeafRange({
diff --git a/src/model/immutable/CharacterMetadata.js b/src/model/immutable/CharacterMetadata.js
index 7b47bd71d3..d737875d2c 100644
--- a/src/model/immutable/CharacterMetadata.js
+++ b/src/model/immutable/CharacterMetadata.js
@@ -14,7 +14,7 @@
 
 import type {DraftInlineStyle} from 'DraftInlineStyle';
 
-var {Map, OrderedSet, Record} = require('immutable');
+const {Map, OrderedSet, Record} = require('immutable');
 
 // Immutable.map is typed such that the value for every key in the map
 // must be the same type
@@ -27,12 +27,12 @@ type CharacterMetadataConfig = {
 
 const EMPTY_SET = OrderedSet();
 
-var defaultRecord: CharacterMetadataConfig = {
+const defaultRecord: CharacterMetadataConfig = {
   style: EMPTY_SET,
   entity: null,
 };
 
-var CharacterMetadataRecord = Record(defaultRecord);
+const CharacterMetadataRecord = Record(defaultRecord);
 
 class CharacterMetadata extends CharacterMetadataRecord {
   getStyle(): DraftInlineStyle {
@@ -51,7 +51,7 @@ class CharacterMetadata extends CharacterMetadataRecord {
     record: CharacterMetadata,
     style: string,
   ): CharacterMetadata {
-    var withStyle = record.set('style', record.getStyle().add(style));
+    const withStyle = record.set('style', record.getStyle().add(style));
     return CharacterMetadata.create(withStyle);
   }
 
@@ -59,7 +59,7 @@ class CharacterMetadata extends CharacterMetadataRecord {
     record: CharacterMetadata,
     style: string,
   ): CharacterMetadata {
-    var withoutStyle = record.set('style', record.getStyle().remove(style));
+    const withoutStyle = record.set('style', record.getStyle().remove(style));
     return CharacterMetadata.create(withoutStyle);
   }
 
@@ -67,7 +67,7 @@ class CharacterMetadata extends CharacterMetadataRecord {
     record: CharacterMetadata,
     entityKey: ?string,
   ): CharacterMetadata {
-    var withEntity =
+    const withEntity =
       record.getEntity() === entityKey
         ? record
         : record.set('entity', entityKey);
@@ -91,21 +91,21 @@ class CharacterMetadata extends CharacterMetadataRecord {
     };
 
     // Fill in unspecified properties, if necessary.
-    var configMap = Map(defaultConfig).merge(config);
+    const configMap = Map(defaultConfig).merge(config);
 
-    var existing: ?CharacterMetadata = pool.get(configMap);
+    const existing: ?CharacterMetadata = pool.get(configMap);
     if (existing) {
       return existing;
     }
 
-    var newCharacter = new CharacterMetadata(configMap);
+    const newCharacter = new CharacterMetadata(configMap);
     pool = pool.set(configMap, newCharacter);
     return newCharacter;
   }
 }
 
-var EMPTY = new CharacterMetadata();
-var pool: Map<Map<any, any>, CharacterMetadata> = Map([
+const EMPTY = new CharacterMetadata();
+let pool: Map<Map<any, any>, CharacterMetadata> = Map([
   [Map(defaultRecord), EMPTY],
 ]);
 
diff --git a/src/model/immutable/ContentBlock.js b/src/model/immutable/ContentBlock.js
index 9abe28aaa4..4e32b4a1c9 100644
--- a/src/model/immutable/ContentBlock.js
+++ b/src/model/immutable/ContentBlock.js
@@ -84,12 +84,12 @@ class ContentBlock extends ContentBlockRecord implements BlockNode {
   }
 
   getInlineStyleAt(offset: number): DraftInlineStyle {
-    var character = this.getCharacterList().get(offset);
+    const character = this.getCharacterList().get(offset);
     return character ? character.getStyle() : EMPTY_SET;
   }
 
   getEntityAt(offset: number): ?string {
-    var character = this.getCharacterList().get(offset);
+    const character = this.getCharacterList().get(offset);
     return character ? character.getEntity() : null;
   }
 
diff --git a/src/model/immutable/ContentBlockNode.js b/src/model/immutable/ContentBlockNode.js
index 8ec5fde408..2396750061 100644
--- a/src/model/immutable/ContentBlockNode.js
+++ b/src/model/immutable/ContentBlockNode.js
@@ -111,12 +111,12 @@ class ContentBlockNode extends Record(defaultRecord) implements BlockNode {
   }
 
   getInlineStyleAt(offset: number): DraftInlineStyle {
-    var character = this.getCharacterList().get(offset);
+    const character = this.getCharacterList().get(offset);
     return character ? character.getStyle() : EMPTY_SET;
   }
 
   getEntityAt(offset: number): ?string {
-    var character = this.getCharacterList().get(offset);
+    const character = this.getCharacterList().get(offset);
     return character ? character.getEntity() : null;
   }
 
diff --git a/src/model/immutable/ContentState.js b/src/model/immutable/ContentState.js
index 4c3bf2fb28..78010155fa 100644
--- a/src/model/immutable/ContentState.js
+++ b/src/model/immutable/ContentState.js
@@ -71,7 +71,7 @@ class ContentState extends ContentStateRecord {
   }
 
   getBlockForKey(key: string): BlockNodeRecord {
-    var block: BlockNodeRecord = this.getBlockMap().get(key);
+    const block: BlockNodeRecord = this.getBlockMap().get(key);
     return block;
   }
 
@@ -133,7 +133,7 @@ class ContentState extends ContentStateRecord {
   }
 
   hasText(): boolean {
-    var blockMap = this.getBlockMap();
+    const blockMap = this.getBlockMap();
     return blockMap.size > 1 || blockMap.first().getLength() > 0;
   }
 
@@ -177,8 +177,8 @@ class ContentState extends ContentStateRecord {
   ): ContentState {
     // TODO: remove this when we completely deprecate the old entity API
     const theBlocks = Array.isArray(blocks) ? blocks : blocks.contentBlocks;
-    var blockMap = BlockMapBuilder.createFromArray(theBlocks);
-    var selectionState = blockMap.isEmpty()
+    const blockMap = BlockMapBuilder.createFromArray(theBlocks);
+    const selectionState = blockMap.isEmpty()
       ? new SelectionState()
       : SelectionState.createEmpty(blockMap.first().getKey());
     return new ContentState({
diff --git a/src/model/immutable/EditorBidiService.js b/src/model/immutable/EditorBidiService.js
index 63ac811392..7de0cc704f 100644
--- a/src/model/immutable/EditorBidiService.js
+++ b/src/model/immutable/EditorBidiService.js
@@ -14,16 +14,16 @@
 
 import type ContentState from 'ContentState';
 
-var Immutable = require('immutable');
-var UnicodeBidiService = require('UnicodeBidiService');
+const Immutable = require('immutable');
+const UnicodeBidiService = require('UnicodeBidiService');
 
-var nullthrows = require('nullthrows');
+const nullthrows = require('nullthrows');
 
-var {OrderedMap} = Immutable;
+const {OrderedMap} = Immutable;
 
-var bidiService;
+let bidiService;
 
-var EditorBidiService = {
+const EditorBidiService = {
   getDirectionMap: function(
     content: ContentState,
     prevBidiMap: ?OrderedMap<any, any>,
@@ -34,11 +34,11 @@ var EditorBidiService = {
       bidiService.reset();
     }
 
-    var blockMap = content.getBlockMap();
-    var nextBidi = blockMap
+    const blockMap = content.getBlockMap();
+    const nextBidi = blockMap
       .valueSeq()
       .map(block => nullthrows(bidiService).getDirection(block.getText()));
-    var bidiMap = OrderedMap(blockMap.keySeq().zip(nextBidi));
+    const bidiMap = OrderedMap(blockMap.keySeq().zip(nextBidi));
 
     if (prevBidiMap != null && Immutable.is(prevBidiMap, bidiMap)) {
       return prevBidiMap;
diff --git a/src/model/immutable/EditorState.js b/src/model/immutable/EditorState.js
index f4f7928a7b..6c1b40c37f 100644
--- a/src/model/immutable/EditorState.js
+++ b/src/model/immutable/EditorState.js
@@ -19,13 +19,13 @@ import type {EditorChangeType} from 'EditorChangeType';
 import type {EntityMap} from 'EntityMap';
 import type {List, OrderedMap} from 'immutable';
 
-var BlockTree = require('BlockTree');
-var ContentState = require('ContentState');
-var EditorBidiService = require('EditorBidiService');
-var Immutable = require('immutable');
-var SelectionState = require('SelectionState');
+const BlockTree = require('BlockTree');
+const ContentState = require('ContentState');
+const EditorBidiService = require('EditorBidiService');
+const Immutable = require('immutable');
+const SelectionState = require('SelectionState');
 
-var {OrderedSet, Record, Stack} = Immutable;
+const {OrderedSet, Record, Stack} = Immutable;
 
 type EditorStateRecordType = {
   allowUndo: boolean,
@@ -43,7 +43,7 @@ type EditorStateRecordType = {
   undoStack: Stack<ContentState>,
 };
 
-var defaultRecord: EditorStateRecordType = {
+const defaultRecord: EditorStateRecordType = {
   allowUndo: true,
   currentContent: null,
   decorator: null,
@@ -59,7 +59,7 @@ var defaultRecord: EditorStateRecordType = {
   undoStack: Stack(),
 };
 
-var EditorStateRecord = Record(defaultRecord);
+const EditorStateRecord = Record(defaultRecord);
 
 class EditorState {
   _immutable: EditorStateRecord;
@@ -75,7 +75,7 @@ class EditorState {
     contentState: ContentState,
     decorator?: ?DraftDecoratorType,
   ): EditorState {
-    var firstKey = contentState
+    const firstKey = contentState
       .getBlockMap()
       .first()
       .getKey();
@@ -89,8 +89,8 @@ class EditorState {
   }
 
   static create(config: Object): EditorState {
-    var {currentContent, decorator} = config;
-    var recordConfig = {
+    const {currentContent, decorator} = config;
+    const recordConfig = {
       ...config,
       treeMap: generateNewTreeMap(currentContent, decorator),
       directionMap: EditorBidiService.getDirectionMap(currentContent),
@@ -99,20 +99,20 @@ class EditorState {
   }
 
   static set(editorState: EditorState, put: Object): EditorState {
-    var map = editorState.getImmutable().withMutations(state => {
-      var existingDecorator = state.get('decorator');
-      var decorator = existingDecorator;
+    const map = editorState.getImmutable().withMutations(state => {
+      const existingDecorator = state.get('decorator');
+      let decorator = existingDecorator;
       if (put.decorator === null) {
         decorator = null;
       } else if (put.decorator) {
         decorator = put.decorator;
       }
 
-      var newContent = put.currentContent || editorState.getCurrentContent();
+      const newContent = put.currentContent || editorState.getCurrentContent();
 
       if (decorator !== existingDecorator) {
-        var treeMap: OrderedMap<any, any> = state.get('treeMap');
-        var newTreeMap;
+        const treeMap: OrderedMap<any, any> = state.get('treeMap');
+        let newTreeMap;
         if (decorator && existingDecorator) {
           newTreeMap = regenerateTreeForNewDecorator(
             newContent,
@@ -133,7 +133,7 @@ class EditorState {
         return;
       }
 
-      var existingContent = editorState.getCurrentContent();
+      const existingContent = editorState.getCurrentContent();
       if (newContent !== existingContent) {
         state.set(
           'treeMap',
@@ -221,13 +221,13 @@ class EditorState {
    * based on the location of the selection state.
    */
   getCurrentInlineStyle(): DraftInlineStyle {
-    var override = this.getInlineStyleOverride();
+    const override = this.getInlineStyleOverride();
     if (override != null) {
       return override;
     }
 
-    var content = this.getCurrentContent();
-    var selection = this.getSelection();
+    const content = this.getCurrentContent();
+    const selection = this.getSelection();
 
     if (selection.isCollapsed()) {
       return getInlineStyleForCollapsedSelection(content, selection);
@@ -241,7 +241,7 @@ class EditorState {
   }
 
   isSelectionAtStartOfContent(): boolean {
-    var firstKey = this.getCurrentContent()
+    const firstKey = this.getCurrentContent()
       .getBlockMap()
       .first()
       .getKey();
@@ -249,10 +249,10 @@ class EditorState {
   }
 
   isSelectionAtEndOfContent(): boolean {
-    var content = this.getCurrentContent();
-    var blockMap = content.getBlockMap();
-    var last = blockMap.last();
-    var end = last.getLength();
+    const content = this.getCurrentContent();
+    const blockMap = content.getBlockMap();
+    const last = blockMap.last();
+    const end = last.getLength();
     return this.getSelection().hasEdgeWithin(last.getKey(), end, end);
   }
 
@@ -301,10 +301,10 @@ class EditorState {
    * Move selection to the end of the editor without forcing focus.
    */
   static moveSelectionToEnd(editorState: EditorState): EditorState {
-    var content = editorState.getCurrentContent();
-    var lastBlock = content.getLastBlock();
-    var lastKey = lastBlock.getKey();
-    var length = lastBlock.getLength();
+    const content = editorState.getCurrentContent();
+    const lastBlock = content.getLastBlock();
+    const lastKey = lastBlock.getKey();
+    const length = lastBlock.getLength();
 
     return EditorState.acceptSelection(
       editorState,
@@ -324,7 +324,7 @@ class EditorState {
    * to allow the user to continue working seamlessly.
    */
   static moveFocusToEnd(editorState: EditorState): EditorState {
-    var afterSelectionMove = EditorState.moveSelectionToEnd(editorState);
+    const afterSelectionMove = EditorState.moveSelectionToEnd(editorState);
     return EditorState.forceSelection(
       afterSelectionMove,
       afterSelectionMove.getSelection(),
@@ -345,8 +345,8 @@ class EditorState {
       return editorState;
     }
 
-    var forceSelection = changeType !== 'insert-characters';
-    var directionMap = EditorBidiService.getDirectionMap(
+    const forceSelection = changeType !== 'insert-characters';
+    const directionMap = EditorBidiService.getDirectionMap(
       contentState,
       editorState.getDirectionMap(),
     );
@@ -362,10 +362,10 @@ class EditorState {
       });
     }
 
-    var selection = editorState.getSelection();
-    var currentContent = editorState.getCurrentContent();
-    var undoStack = editorState.getUndoStack();
-    var newContent = contentState;
+    const selection = editorState.getSelection();
+    const currentContent = editorState.getCurrentContent();
+    let undoStack = editorState.getUndoStack();
+    let newContent = contentState;
 
     if (
       selection !== currentContent.getSelectionAfter() ||
@@ -388,7 +388,7 @@ class EditorState {
     let inlineStyleOverride = editorState.getInlineStyleOverride();
 
     // Don't discard inline style overrides for the following change types:
-    var overrideChangeTypes = [
+    const overrideChangeTypes = [
       'adjust-depth',
       'change-block-type',
       'split-block',
@@ -398,7 +398,7 @@ class EditorState {
       inlineStyleOverride = null;
     }
 
-    var editorStateChanges = {
+    const editorStateChanges = {
       currentContent: newContent,
       directionMap,
       undoStack,
@@ -421,14 +421,14 @@ class EditorState {
       return editorState;
     }
 
-    var undoStack = editorState.getUndoStack();
-    var newCurrentContent = undoStack.peek();
+    const undoStack = editorState.getUndoStack();
+    const newCurrentContent = undoStack.peek();
     if (!newCurrentContent) {
       return editorState;
     }
 
-    var currentContent = editorState.getCurrentContent();
-    var directionMap = EditorBidiService.getDirectionMap(
+    const currentContent = editorState.getCurrentContent();
+    const directionMap = EditorBidiService.getDirectionMap(
       newCurrentContent,
       editorState.getDirectionMap(),
     );
@@ -455,14 +455,14 @@ class EditorState {
       return editorState;
     }
 
-    var redoStack = editorState.getRedoStack();
-    var newCurrentContent = redoStack.peek();
+    const redoStack = editorState.getRedoStack();
+    const newCurrentContent = redoStack.peek();
     if (!newCurrentContent) {
       return editorState;
     }
 
-    var currentContent = editorState.getCurrentContent();
-    var directionMap = EditorBidiService.getDirectionMap(
+    const currentContent = editorState.getCurrentContent();
+    const directionMap = EditorBidiService.getDirectionMap(
       newCurrentContent,
       editorState.getDirectionMap(),
     );
@@ -540,8 +540,8 @@ function regenerateTreeForNewBlocks(
   const contentState = editorState
     .getCurrentContent()
     .set('entityMap', newEntityMap);
-  var prevBlockMap = contentState.getBlockMap();
-  var prevTreeMap = editorState.getImmutable().get('treeMap');
+  const prevBlockMap = contentState.getBlockMap();
+  const prevTreeMap = editorState.getImmutable().get('treeMap');
   return prevTreeMap.merge(
     newBlockMap
       .toSeq()
@@ -587,7 +587,7 @@ function mustBecomeBoundary(
   editorState: EditorState,
   changeType: EditorChangeType,
 ): boolean {
-  var lastChangeType = editorState.getLastChangeType();
+  const lastChangeType = editorState.getLastChangeType();
   return (
     changeType !== lastChangeType ||
     (changeType !== 'insert-characters' &&
@@ -600,9 +600,9 @@ function getInlineStyleForCollapsedSelection(
   content: ContentState,
   selection: SelectionState,
 ): DraftInlineStyle {
-  var startKey = selection.getStartKey();
-  var startOffset = selection.getStartOffset();
-  var startBlock = content.getBlockForKey(startKey);
+  const startKey = selection.getStartKey();
+  const startOffset = selection.getStartOffset();
+  const startBlock = content.getBlockForKey(startKey);
 
   // If the cursor is not at the start of the block, look backward to
   // preserve the style of the preceding character.
@@ -624,9 +624,9 @@ function getInlineStyleForNonCollapsedSelection(
   content: ContentState,
   selection: SelectionState,
 ): DraftInlineStyle {
-  var startKey = selection.getStartKey();
-  var startOffset = selection.getStartOffset();
-  var startBlock = content.getBlockForKey(startKey);
+  const startKey = selection.getStartKey();
+  const startOffset = selection.getStartOffset();
+  const startBlock = content.getBlockForKey(startKey);
 
   // If there is a character just inside the selection, use its style.
   if (startOffset < startBlock.getLength()) {
@@ -647,7 +647,7 @@ function lookUpwardForInlineStyle(
   content: ContentState,
   fromKey: string,
 ): DraftInlineStyle {
-  var lastNonEmpty = content
+  const lastNonEmpty = content
     .getBlockMap()
     .reverse()
     .skipUntil((_, k) => k === fromKey)
diff --git a/src/model/immutable/SelectionState.js b/src/model/immutable/SelectionState.js
index a503ef8b46..12cdd89172 100644
--- a/src/model/immutable/SelectionState.js
+++ b/src/model/immutable/SelectionState.js
@@ -12,11 +12,11 @@
 
 'use strict';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var {Record} = Immutable;
+const {Record} = Immutable;
 
-var defaultRecord: {
+const defaultRecord: {
   anchorKey: string,
   anchorOffset: number,
   focusKey: string,
@@ -32,7 +32,7 @@ var defaultRecord: {
   hasFocus: false,
 };
 
-var SelectionStateRecord = Record(defaultRecord);
+const SelectionStateRecord = Record(defaultRecord);
 
 class SelectionState extends SelectionStateRecord {
   serialize(): string {
@@ -84,12 +84,12 @@ class SelectionState extends SelectionStateRecord {
    * SelectionState.
    */
   hasEdgeWithin(blockKey: string, start: number, end: number): boolean {
-    var anchorKey = this.getAnchorKey();
-    var focusKey = this.getFocusKey();
+    const anchorKey = this.getAnchorKey();
+    const focusKey = this.getFocusKey();
 
     if (anchorKey === focusKey && anchorKey === blockKey) {
-      var selectionStart = this.getStartOffset();
-      var selectionEnd = this.getEndOffset();
+      const selectionStart = this.getStartOffset();
+      const selectionEnd = this.getEndOffset();
       return start <= selectionEnd && selectionStart <= end;
     }
 
@@ -97,7 +97,7 @@ class SelectionState extends SelectionStateRecord {
       return false;
     }
 
-    var offsetToCheck =
+    const offsetToCheck =
       blockKey === anchorKey ? this.getAnchorOffset() : this.getFocusOffset();
 
     return start <= offsetToCheck && end >= offsetToCheck;
diff --git a/src/model/immutable/findRangesImmutable.js b/src/model/immutable/findRangesImmutable.js
index 45d77b8f1f..06a7dc1365 100644
--- a/src/model/immutable/findRangesImmutable.js
+++ b/src/model/immutable/findRangesImmutable.js
@@ -31,7 +31,7 @@ function findRangesImmutable<T>(
     return;
   }
 
-  var cursor: number = 0;
+  let cursor: number = 0;
 
   haystack.reduce((value: T, nextValue, nextIndex) => {
     if (!areEqualFn(value, nextValue)) {
diff --git a/src/model/modifier/DraftEntitySegments.js b/src/model/modifier/DraftEntitySegments.js
index 73bf76c33a..4585c5d818 100644
--- a/src/model/modifier/DraftEntitySegments.js
+++ b/src/model/modifier/DraftEntitySegments.js
@@ -38,7 +38,7 @@ import type {DraftRemovalDirection} from 'DraftRemovalDirection';
  *       'John F. Kennedy' -> 'F. Kennedy'
  *            ^
  */
-var DraftEntitySegments = {
+const DraftEntitySegments = {
   getRemovalRange: function(
     selectionStart: number,
     selectionEnd: number,
@@ -46,7 +46,7 @@ var DraftEntitySegments = {
     entityStart: number,
     direction: DraftRemovalDirection,
   ): DraftRange {
-    var segments = text.split(' ');
+    let segments = text.split(' ');
     segments = segments.map((/*string*/ segment, /*number*/ ii) => {
       if (direction === 'forward') {
         if (ii > 0) {
@@ -58,13 +58,13 @@ var DraftEntitySegments = {
       return segment;
     });
 
-    var segmentStart = entityStart;
-    var segmentEnd;
-    var segment;
-    var removalStart: any = null;
-    var removalEnd: any = null;
+    let segmentStart = entityStart;
+    let segmentEnd;
+    let segment;
+    let removalStart: any = null;
+    let removalEnd: any = null;
 
-    for (var jj = 0; jj < segments.length; jj++) {
+    for (let jj = 0; jj < segments.length; jj++) {
       segment = segments[jj];
       segmentEnd = segmentStart + segment.length;
 
@@ -83,9 +83,9 @@ var DraftEntitySegments = {
       segmentStart = segmentEnd;
     }
 
-    var entityEnd = entityStart + text.length;
-    var atStart = removalStart === entityStart;
-    var atEnd = removalEnd === entityEnd;
+    const entityEnd = entityStart + text.length;
+    const atStart = removalStart === entityStart;
+    const atEnd = removalEnd === entityEnd;
 
     if ((!atStart && atEnd) || (atStart && !atEnd)) {
       if (direction === 'forward') {
diff --git a/src/model/modifier/DraftModifier.js b/src/model/modifier/DraftModifier.js
index d1c0027e05..8cc4fe12fe 100644
--- a/src/model/modifier/DraftModifier.js
+++ b/src/model/modifier/DraftModifier.js
@@ -20,21 +20,21 @@ import type {DraftRemovalDirection} from 'DraftRemovalDirection';
 import type SelectionState from 'SelectionState';
 import type {Map} from 'immutable';
 
-var CharacterMetadata = require('CharacterMetadata');
-var ContentStateInlineStyle = require('ContentStateInlineStyle');
-var Immutable = require('immutable');
+const CharacterMetadata = require('CharacterMetadata');
+const ContentStateInlineStyle = require('ContentStateInlineStyle');
+const Immutable = require('immutable');
 
-var applyEntityToContentState = require('applyEntityToContentState');
-var getCharacterRemovalRange = require('getCharacterRemovalRange');
-var getContentStateFragment = require('getContentStateFragment');
-var gkx = require('gkx');
-var insertFragmentIntoContentState = require('insertFragmentIntoContentState');
-var insertTextIntoContentState = require('insertTextIntoContentState');
-var invariant = require('invariant');
-var modifyBlockForContentState = require('modifyBlockForContentState');
-var removeEntitiesAtEdges = require('removeEntitiesAtEdges');
-var removeRangeFromContentState = require('removeRangeFromContentState');
-var splitBlockInContentState = require('splitBlockInContentState');
+const applyEntityToContentState = require('applyEntityToContentState');
+const getCharacterRemovalRange = require('getCharacterRemovalRange');
+const getContentStateFragment = require('getContentStateFragment');
+const gkx = require('gkx');
+const insertFragmentIntoContentState = require('insertFragmentIntoContentState');
+const insertTextIntoContentState = require('insertTextIntoContentState');
+const invariant = require('invariant');
+const modifyBlockForContentState = require('modifyBlockForContentState');
+const removeEntitiesAtEdges = require('removeEntitiesAtEdges');
+const removeRangeFromContentState = require('removeRangeFromContentState');
+const splitBlockInContentState = require('splitBlockInContentState');
 
 const {OrderedSet} = Immutable;
 
@@ -48,7 +48,7 @@ const {OrderedSet} = Immutable;
  *
  * These functions encapsulate some of the most common transaction sequences.
  */
-var DraftModifier = {
+const DraftModifier = {
   replaceText: function(
     contentState: ContentState,
     rangeToReplace: SelectionState,
@@ -56,13 +56,13 @@ var DraftModifier = {
     inlineStyle?: DraftInlineStyle,
     entityKey?: ?string,
   ): ContentState {
-    var withoutEntities = removeEntitiesAtEdges(contentState, rangeToReplace);
-    var withoutText = removeRangeFromContentState(
+    const withoutEntities = removeEntitiesAtEdges(contentState, rangeToReplace);
+    const withoutText = removeRangeFromContentState(
       withoutEntities,
       rangeToReplace,
     );
 
-    var character = CharacterMetadata.create({
+    const character = CharacterMetadata.create({
       style: inlineStyle || OrderedSet(),
       entity: entityKey || null,
     });
@@ -100,9 +100,9 @@ var DraftModifier = {
     removalRange: SelectionState,
     targetRange: SelectionState,
   ): ContentState {
-    var movedFragment = getContentStateFragment(contentState, removalRange);
+    const movedFragment = getContentStateFragment(contentState, removalRange);
 
-    var afterRemoval = DraftModifier.removeRange(
+    const afterRemoval = DraftModifier.removeRange(
       contentState,
       removalRange,
       'backward',
@@ -120,8 +120,11 @@ var DraftModifier = {
     targetRange: SelectionState,
     fragment: BlockMap,
   ): ContentState {
-    var withoutEntities = removeEntitiesAtEdges(contentState, targetRange);
-    var withoutText = removeRangeFromContentState(withoutEntities, targetRange);
+    const withoutEntities = removeEntitiesAtEdges(contentState, targetRange);
+    const withoutText = removeRangeFromContentState(
+      withoutEntities,
+      targetRange,
+    );
 
     return insertFragmentIntoContentState(
       withoutText,
@@ -182,7 +185,7 @@ var DraftModifier = {
       );
     }
 
-    var withoutEntities = removeEntitiesAtEdges(
+    const withoutEntities = removeEntitiesAtEdges(
       contentState,
       adjustedRemovalRange,
     );
@@ -193,8 +196,8 @@ var DraftModifier = {
     contentState: ContentState,
     selectionState: SelectionState,
   ): ContentState {
-    var withoutEntities = removeEntitiesAtEdges(contentState, selectionState);
-    var withoutText = removeRangeFromContentState(
+    const withoutEntities = removeEntitiesAtEdges(contentState, selectionState);
+    const withoutText = removeRangeFromContentState(
       withoutEntities,
       selectionState,
     );
@@ -264,7 +267,7 @@ var DraftModifier = {
     selectionState: SelectionState,
     entityKey: ?string,
   ): ContentState {
-    var withoutEntities = removeEntitiesAtEdges(contentState, selectionState);
+    const withoutEntities = removeEntitiesAtEdges(contentState, selectionState);
     return applyEntityToContentState(
       withoutEntities,
       selectionState,
diff --git a/src/model/modifier/DraftRemovableWord.js b/src/model/modifier/DraftRemovableWord.js
index ce638ccc8c..6f48eafb76 100644
--- a/src/model/modifier/DraftRemovableWord.js
+++ b/src/model/modifier/DraftRemovableWord.js
@@ -12,21 +12,21 @@
 
 'use strict';
 
-var TokenizeUtil = require('TokenizeUtil');
+const TokenizeUtil = require('TokenizeUtil');
 
-var punctuation = TokenizeUtil.getPunctuation();
+const punctuation = TokenizeUtil.getPunctuation();
 
 // The apostrophe and curly single quotes behave in a curious way: when
 // surrounded on both sides by word characters, they behave as word chars; when
 // either neighbor is punctuation or an end of the string, they behave as
 // punctuation.
-var CHAMELEON_CHARS = "['\u2018\u2019]";
+const CHAMELEON_CHARS = "['\u2018\u2019]";
 
 // Remove the underscore, which should count as part of the removable word. The
 // "chameleon chars" also count as punctuation in this regex.
-var WHITESPACE_AND_PUNCTUATION = '\\s|(?![_])' + punctuation;
+const WHITESPACE_AND_PUNCTUATION = '\\s|(?![_])' + punctuation;
 
-var DELETE_STRING =
+const DELETE_STRING =
   '^' +
   '(?:' +
   WHITESPACE_AND_PUNCTUATION +
@@ -39,9 +39,9 @@ var DELETE_STRING =
   '(?:(?!' +
   WHITESPACE_AND_PUNCTUATION +
   ').)';
-var DELETE_REGEX = new RegExp(DELETE_STRING);
+const DELETE_REGEX = new RegExp(DELETE_STRING);
 
-var BACKSPACE_STRING =
+const BACKSPACE_STRING =
   '(?:(?!' +
   WHITESPACE_AND_PUNCTUATION +
   ').)' +
@@ -54,16 +54,16 @@ var BACKSPACE_STRING =
   WHITESPACE_AND_PUNCTUATION +
   ')*' +
   '$';
-var BACKSPACE_REGEX = new RegExp(BACKSPACE_STRING);
+const BACKSPACE_REGEX = new RegExp(BACKSPACE_STRING);
 
 function getRemovableWord(text: string, isBackward: boolean): string {
-  var matches = isBackward
+  const matches = isBackward
     ? BACKSPACE_REGEX.exec(text)
     : DELETE_REGEX.exec(text);
   return matches ? matches[0] : text;
 }
 
-var DraftRemovableWord = {
+const DraftRemovableWord = {
   getBackward: function(text: string): string {
     return getRemovableWord(text, true);
   },
diff --git a/src/model/modifier/RichTextEditorUtil.js b/src/model/modifier/RichTextEditorUtil.js
index 34b2a33476..455d2d124e 100644
--- a/src/model/modifier/RichTextEditorUtil.js
+++ b/src/model/modifier/RichTextEditorUtil.js
@@ -26,7 +26,7 @@ const nullthrows = require('nullthrows');
 
 const RichTextEditorUtil = {
   currentBlockContainsLink: function(editorState: EditorState): boolean {
-    var selection = editorState.getSelection();
+    const selection = editorState.getSelection();
     const contentState = editorState.getCurrentContent();
     const entityMap = contentState.getEntityMap();
     return contentState
@@ -34,13 +34,13 @@ const RichTextEditorUtil = {
       .getCharacterList()
       .slice(selection.getStartOffset(), selection.getEndOffset())
       .some(v => {
-        var entity = v.getEntity();
+        const entity = v.getEntity();
         return !!entity && entityMap.__get(entity).getType() === 'LINK';
       });
   },
 
   getCurrentBlockType: function(editorState: EditorState): DraftBlockType {
-    var selection = editorState.getSelection();
+    const selection = editorState.getSelection();
     return editorState
       .getCurrentContent()
       .getBlockForKey(selection.getStartKey())
@@ -79,7 +79,7 @@ const RichTextEditorUtil = {
   },
 
   insertSoftNewline: function(editorState: EditorState): EditorState {
-    var contentState = DraftModifier.insertText(
+    const contentState = DraftModifier.insertText(
       editorState.getCurrentContent(),
       editorState.getSelection(),
       '\n',
@@ -87,7 +87,7 @@ const RichTextEditorUtil = {
       null,
     );
 
-    var newEditorState = EditorState.push(
+    const newEditorState = EditorState.push(
       editorState,
       contentState,
       'insert-characters',
@@ -104,7 +104,7 @@ const RichTextEditorUtil = {
    * just remove the existing style.
    */
   onBackspace: function(editorState: EditorState): ?EditorState {
-    var selection = editorState.getSelection();
+    const selection = editorState.getSelection();
     if (
       !selection.isCollapsed() ||
       selection.getAnchorOffset() ||
@@ -114,13 +114,13 @@ const RichTextEditorUtil = {
     }
 
     // First, try to remove a preceding atomic block.
-    var content = editorState.getCurrentContent();
-    var startKey = selection.getStartKey();
-    var blockBefore = content.getBlockBefore(startKey);
+    const content = editorState.getCurrentContent();
+    const startKey = selection.getStartKey();
+    const blockBefore = content.getBlockBefore(startKey);
 
     if (blockBefore && blockBefore.getType() === 'atomic') {
       const blockMap = content.getBlockMap().delete(blockBefore.getKey());
-      var withoutAtomicBlock = content.merge({
+      const withoutAtomicBlock = content.merge({
         blockMap,
         selectionAfter: selection,
       });
@@ -134,7 +134,7 @@ const RichTextEditorUtil = {
     }
 
     // If that doesn't succeed, try to remove the current block style.
-    var withoutBlockStyle = RichTextEditorUtil.tryToRemoveBlockStyle(
+    const withoutBlockStyle = RichTextEditorUtil.tryToRemoveBlockStyle(
       editorState,
     );
 
@@ -194,27 +194,27 @@ const RichTextEditorUtil = {
     editorState: EditorState,
     maxDepth: number,
   ): EditorState {
-    var selection = editorState.getSelection();
-    var key = selection.getAnchorKey();
+    const selection = editorState.getSelection();
+    const key = selection.getAnchorKey();
     if (key !== selection.getFocusKey()) {
       return editorState;
     }
 
-    var content = editorState.getCurrentContent();
-    var block = content.getBlockForKey(key);
-    var type = block.getType();
+    const content = editorState.getCurrentContent();
+    const block = content.getBlockForKey(key);
+    const type = block.getType();
     if (type !== 'unordered-list-item' && type !== 'ordered-list-item') {
       return editorState;
     }
 
     event.preventDefault();
 
-    var depth = block.getDepth();
+    const depth = block.getDepth();
     if (!event.shiftKey && depth === maxDepth) {
       return editorState;
     }
 
-    var withAdjustment = adjustBlockDepthForContentState(
+    const withAdjustment = adjustBlockDepthForContentState(
       content,
       selection,
       event.shiftKey ? -1 : 1,
@@ -228,18 +228,18 @@ const RichTextEditorUtil = {
     editorState: EditorState,
     blockType: DraftBlockType,
   ): EditorState {
-    var selection = editorState.getSelection();
-    var startKey = selection.getStartKey();
-    var endKey = selection.getEndKey();
-    var content = editorState.getCurrentContent();
-    var target = selection;
+    const selection = editorState.getSelection();
+    const startKey = selection.getStartKey();
+    let endKey = selection.getEndKey();
+    const content = editorState.getCurrentContent();
+    let target = selection;
 
     // Triple-click can lead to a selection that includes offset 0 of the
     // following block. The `SelectionState` for this case is accurate, but
     // we should avoid toggling block type for the trailing block because it
     // is a confusing interaction.
     if (startKey !== endKey && selection.getEndOffset() === 0) {
-      var blockBefore = nullthrows(content.getBlockBefore(endKey));
+      const blockBefore = nullthrows(content.getBlockBefore(endKey));
       endKey = blockBefore.getKey();
       target = target.merge({
         anchorKey: startKey,
@@ -250,7 +250,7 @@ const RichTextEditorUtil = {
       });
     }
 
-    var hasAtomicBlock = content
+    const hasAtomicBlock = content
       .getBlockMap()
       .skipWhile((_, k) => k !== startKey)
       .reverse()
@@ -261,7 +261,7 @@ const RichTextEditorUtil = {
       return editorState;
     }
 
-    var typeToSet =
+    const typeToSet =
       content.getBlockForKey(startKey).getType() === blockType
         ? 'unstyled'
         : blockType;
@@ -274,9 +274,9 @@ const RichTextEditorUtil = {
   },
 
   toggleCode: function(editorState: EditorState): EditorState {
-    var selection = editorState.getSelection();
-    var anchorKey = selection.getAnchorKey();
-    var focusKey = selection.getFocusKey();
+    const selection = editorState.getSelection();
+    const anchorKey = selection.getAnchorKey();
+    const focusKey = selection.getFocusKey();
 
     if (selection.isCollapsed() || anchorKey !== focusKey) {
       return RichTextEditorUtil.toggleBlockType(editorState, 'code-block');
@@ -295,8 +295,8 @@ const RichTextEditorUtil = {
     editorState: EditorState,
     inlineStyle: string,
   ): EditorState {
-    var selection = editorState.getSelection();
-    var currentStyle = editorState.getCurrentInlineStyle();
+    const selection = editorState.getSelection();
+    const currentStyle = editorState.getCurrentInlineStyle();
 
     // If the selection is collapsed, toggle the specified style on or off and
     // set the result as the new inline style override. This will then be
@@ -312,8 +312,8 @@ const RichTextEditorUtil = {
 
     // If characters are selected, immediately apply or remove the
     // inline style on the document state itself.
-    var content = editorState.getCurrentContent();
-    var newContent;
+    const content = editorState.getCurrentContent();
+    let newContent;
 
     // If the style is already present for the selection range, remove it.
     // Otherwise, apply it.
@@ -339,7 +339,7 @@ const RichTextEditorUtil = {
     targetSelection: SelectionState,
     entityKey: ?string,
   ): EditorState {
-    var withoutLink = DraftModifier.applyEntity(
+    const withoutLink = DraftModifier.applyEntity(
       editorState.getCurrentContent(),
       targetSelection,
       entityKey,
@@ -353,15 +353,15 @@ const RichTextEditorUtil = {
    * type to 'unstyled'. Returns null if selection does not meet that criteria.
    */
   tryToRemoveBlockStyle: function(editorState: EditorState): ?ContentState {
-    var selection = editorState.getSelection();
-    var offset = selection.getAnchorOffset();
+    const selection = editorState.getSelection();
+    const offset = selection.getAnchorOffset();
     if (selection.isCollapsed() && offset === 0) {
-      var key = selection.getAnchorKey();
-      var content = editorState.getCurrentContent();
-      var block = content.getBlockForKey(key);
+      const key = selection.getAnchorKey();
+      const content = editorState.getCurrentContent();
+      const block = content.getBlockForKey(key);
 
-      var type = block.getType();
-      var blockBefore = content.getBlockBefore(key);
+      const type = block.getType();
+      const blockBefore = content.getBlockBefore(key);
       if (
         type === 'code-block' &&
         blockBefore &&
diff --git a/src/model/modifier/getCharacterRemovalRange.js b/src/model/modifier/getCharacterRemovalRange.js
index d22d9b91c3..a4f748a176 100644
--- a/src/model/modifier/getCharacterRemovalRange.js
+++ b/src/model/modifier/getCharacterRemovalRange.js
@@ -17,10 +17,10 @@ import type {DraftRemovalDirection} from 'DraftRemovalDirection';
 import type {EntityMap} from 'EntityMap';
 import type SelectionState from 'SelectionState';
 
-var DraftEntitySegments = require('DraftEntitySegments');
+const DraftEntitySegments = require('DraftEntitySegments');
 
-var getRangesForDraftEntity = require('getRangesForDraftEntity');
-var invariant = require('invariant');
+const getRangesForDraftEntity = require('getRangesForDraftEntity');
+const invariant = require('invariant');
 
 /**
  * Given a SelectionState and a removal direction, determine the entire range
@@ -38,14 +38,14 @@ function getCharacterRemovalRange(
   selectionState: SelectionState,
   direction: DraftRemovalDirection,
 ): SelectionState {
-  var start = selectionState.getStartOffset();
-  var end = selectionState.getEndOffset();
-  var startEntityKey = startBlock.getEntityAt(start);
-  var endEntityKey = endBlock.getEntityAt(end - 1);
+  const start = selectionState.getStartOffset();
+  const end = selectionState.getEndOffset();
+  const startEntityKey = startBlock.getEntityAt(start);
+  const endEntityKey = endBlock.getEntityAt(end - 1);
   if (!startEntityKey && !endEntityKey) {
     return selectionState;
   }
-  var newSelectionState = selectionState;
+  let newSelectionState = selectionState;
   if (startEntityKey && startEntityKey === endEntityKey) {
     newSelectionState = getEntityRemovalRange(
       entityMap,
@@ -121,10 +121,10 @@ function getEntityRemovalRange(
   isEntireSelectionWithinEntity: boolean,
   isEntityAtStart: boolean,
 ): SelectionState {
-  var start = selectionState.getStartOffset();
-  var end = selectionState.getEndOffset();
-  var entity = entityMap.__get(entityKey);
-  var mutability = entity.getMutability();
+  let start = selectionState.getStartOffset();
+  let end = selectionState.getEndOffset();
+  const entity = entityMap.__get(entityKey);
+  const mutability = entity.getMutability();
   const sideToConsider = isEntityAtStart ? start : end;
 
   // `MUTABLE` entities can just have the specified range of text removed
@@ -134,7 +134,7 @@ function getEntityRemovalRange(
   }
 
   // Find the entity range that overlaps with our removal range.
-  var entityRanges = getRangesForDraftEntity(block, entityKey).filter(
+  const entityRanges = getRangesForDraftEntity(block, entityKey).filter(
     range => sideToConsider <= range.end && sideToConsider >= range.start,
   );
 
@@ -143,7 +143,7 @@ function getEntityRemovalRange(
     'There should only be one entity range within this removal range.',
   );
 
-  var entityRange = entityRanges[0];
+  const entityRange = entityRanges[0];
 
   // For `IMMUTABLE` entity types, we will remove the entire entity range.
   if (mutability === 'IMMUTABLE') {
@@ -164,7 +164,7 @@ function getEntityRemovalRange(
     }
   }
 
-  var removalRange = DraftEntitySegments.getRemovalRange(
+  const removalRange = DraftEntitySegments.getRemovalRange(
     start,
     end,
     block.getText().slice(entityRange.start, entityRange.end),
diff --git a/src/model/modifier/getRangesForDraftEntity.js b/src/model/modifier/getRangesForDraftEntity.js
index 94b950e9ad..0c061b6256 100644
--- a/src/model/modifier/getRangesForDraftEntity.js
+++ b/src/model/modifier/getRangesForDraftEntity.js
@@ -15,7 +15,7 @@
 import type {BlockNodeRecord} from 'BlockNodeRecord';
 import type {DraftRange} from 'DraftRange';
 
-var invariant = require('invariant');
+const invariant = require('invariant');
 
 /**
  * Obtain the start and end positions of the range that has the
@@ -29,7 +29,7 @@ function getRangesForDraftEntity(
   block: BlockNodeRecord,
   key: string,
 ): Array<DraftRange> {
-  var ranges = [];
+  const ranges = [];
   block.findEntityRanges(
     c => c.getEntity() === key,
     (start, end) => {
diff --git a/src/model/paste/__mocks__/getSafeBodyFromHTML.js b/src/model/paste/__mocks__/getSafeBodyFromHTML.js
index 623b4d0434..8ae242e204 100644
--- a/src/model/paste/__mocks__/getSafeBodyFromHTML.js
+++ b/src/model/paste/__mocks__/getSafeBodyFromHTML.js
@@ -12,8 +12,8 @@
 // THIS IS PURELY A MOCK TO GET AROUND THE TEST FRAMEWORK
 // Never use this for anything else ever.
 function getUnsafeBodyFromHTML(html) {
-  var fragment = document.createElement('body');
-  var match = html.match(/<body>(.*?)<\/body>/);
+  const fragment = document.createElement('body');
+  const match = html.match(/<body>(.*?)<\/body>/);
   fragment.innerHTML = match ? match[1] : html;
   return fragment;
 }
diff --git a/src/model/paste/getSafeBodyFromHTML.js b/src/model/paste/getSafeBodyFromHTML.js
index b21af81cfa..d742975e1f 100644
--- a/src/model/paste/getSafeBodyFromHTML.js
+++ b/src/model/paste/getSafeBodyFromHTML.js
@@ -12,19 +12,19 @@
 
 'use strict';
 
-var UserAgent = require('UserAgent');
+const UserAgent = require('UserAgent');
 
 const invariant = require('invariant');
 
-var isOldIE = UserAgent.isBrowser('IE <= 9');
+const isOldIE = UserAgent.isBrowser('IE <= 9');
 
 // Provides a dom node that will not execute scripts
 // https://developer.mozilla.org/en-US/docs/Web/API/DOMImplementation.createHTMLDocument
 // https://developer.mozilla.org/en-US/Add-ons/Code_snippets/HTML_to_DOM
 
 function getSafeBodyFromHTML(html: string): ?Element {
-  var doc;
-  var root = null;
+  let doc;
+  let root = null;
   // Provides a safe context
   if (
     !isOldIE &&
diff --git a/src/model/transaction/ContentStateInlineStyle.js b/src/model/transaction/ContentStateInlineStyle.js
index 460edda6d0..c3b68959b3 100644
--- a/src/model/transaction/ContentStateInlineStyle.js
+++ b/src/model/transaction/ContentStateInlineStyle.js
@@ -15,10 +15,10 @@
 import type ContentState from 'ContentState';
 import type SelectionState from 'SelectionState';
 
-var CharacterMetadata = require('CharacterMetadata');
-var {Map} = require('immutable');
+const CharacterMetadata = require('CharacterMetadata');
+const {Map} = require('immutable');
 
-var ContentStateInlineStyle = {
+const ContentStateInlineStyle = {
   add: function(
     contentState: ContentState,
     selectionState: SelectionState,
@@ -42,19 +42,19 @@ function modifyInlineStyle(
   inlineStyle: string,
   addOrRemove: boolean,
 ): ContentState {
-  var blockMap = contentState.getBlockMap();
-  var startKey = selectionState.getStartKey();
-  var startOffset = selectionState.getStartOffset();
-  var endKey = selectionState.getEndKey();
-  var endOffset = selectionState.getEndOffset();
+  const blockMap = contentState.getBlockMap();
+  const startKey = selectionState.getStartKey();
+  const startOffset = selectionState.getStartOffset();
+  const endKey = selectionState.getEndKey();
+  const endOffset = selectionState.getEndOffset();
 
-  var newBlocks = blockMap
+  const newBlocks = blockMap
     .skipUntil((_, k) => k === startKey)
     .takeUntil((_, k) => k === endKey)
     .concat(Map([[endKey, blockMap.get(endKey)]]))
     .map((block, blockKey) => {
-      var sliceStart;
-      var sliceEnd;
+      let sliceStart;
+      let sliceEnd;
 
       if (startKey === endKey) {
         sliceStart = startOffset;
@@ -64,8 +64,8 @@ function modifyInlineStyle(
         sliceEnd = blockKey === endKey ? endOffset : block.getLength();
       }
 
-      var chars = block.getCharacterList();
-      var current;
+      let chars = block.getCharacterList();
+      let current;
       while (sliceStart < sliceEnd) {
         current = chars.get(sliceStart);
         chars = chars.set(
diff --git a/src/model/transaction/adjustBlockDepthForContentState.js b/src/model/transaction/adjustBlockDepthForContentState.js
index 936985a7b2..a75803d4b5 100644
--- a/src/model/transaction/adjustBlockDepthForContentState.js
+++ b/src/model/transaction/adjustBlockDepthForContentState.js
@@ -21,16 +21,16 @@ function adjustBlockDepthForContentState(
   adjustment: number,
   maxDepth: number,
 ): ContentState {
-  var startKey = selectionState.getStartKey();
-  var endKey = selectionState.getEndKey();
-  var blockMap = contentState.getBlockMap();
-  var blocks = blockMap
+  const startKey = selectionState.getStartKey();
+  const endKey = selectionState.getEndKey();
+  let blockMap = contentState.getBlockMap();
+  const blocks = blockMap
     .toSeq()
     .skipUntil((_, k) => k === startKey)
     .takeUntil((_, k) => k === endKey)
     .concat([[endKey, blockMap.get(endKey)]])
     .map(block => {
-      var depth = block.getDepth() + adjustment;
+      let depth = block.getDepth() + adjustment;
       depth = Math.max(0, Math.min(depth, maxDepth));
       return block.set('depth', depth);
     });
diff --git a/src/model/transaction/applyEntityToContentBlock.js b/src/model/transaction/applyEntityToContentBlock.js
index c49ec0ad22..1a1ed361ce 100644
--- a/src/model/transaction/applyEntityToContentBlock.js
+++ b/src/model/transaction/applyEntityToContentBlock.js
@@ -14,7 +14,7 @@
 
 import type {BlockNodeRecord} from 'BlockNodeRecord';
 
-var CharacterMetadata = require('CharacterMetadata');
+const CharacterMetadata = require('CharacterMetadata');
 
 function applyEntityToContentBlock(
   contentBlock: BlockNodeRecord,
@@ -22,7 +22,7 @@ function applyEntityToContentBlock(
   end: number,
   entityKey: ?string,
 ): BlockNodeRecord {
-  var characterList = contentBlock.getCharacterList();
+  let characterList = contentBlock.getCharacterList();
   while (start < end) {
     characterList = characterList.set(
       start,
diff --git a/src/model/transaction/applyEntityToContentState.js b/src/model/transaction/applyEntityToContentState.js
index 22e7c34b34..557a71d7c2 100644
--- a/src/model/transaction/applyEntityToContentState.js
+++ b/src/model/transaction/applyEntityToContentState.js
@@ -15,9 +15,9 @@
 import type ContentState from 'ContentState';
 import type SelectionState from 'SelectionState';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var applyEntityToContentBlock = require('applyEntityToContentBlock');
+const applyEntityToContentBlock = require('applyEntityToContentBlock');
 
 function applyEntityToContentState(
   contentState: ContentState,
diff --git a/src/model/transaction/insertIntoList.js b/src/model/transaction/insertIntoList.js
index 3959fa70f0..847f0011f5 100644
--- a/src/model/transaction/insertIntoList.js
+++ b/src/model/transaction/insertIntoList.js
@@ -31,8 +31,8 @@ function insertIntoList<T>(
       targetList = targetList.unshift(c);
     });
   } else {
-    var head = targetList.slice(0, offset);
-    var tail = targetList.slice(offset);
+    const head = targetList.slice(0, offset);
+    const tail = targetList.slice(offset);
     targetList = head.concat(toInsert, tail).toList();
   }
   return targetList;
diff --git a/src/model/transaction/insertTextIntoContentState.js b/src/model/transaction/insertTextIntoContentState.js
index ced592fdb3..d0a1b8dc40 100644
--- a/src/model/transaction/insertTextIntoContentState.js
+++ b/src/model/transaction/insertTextIntoContentState.js
@@ -12,12 +12,12 @@
 
 'use strict';
 
-var Immutable = require('immutable');
+const Immutable = require('immutable');
 
-var insertIntoList = require('insertIntoList');
-var invariant = require('invariant');
+const insertIntoList = require('insertIntoList');
+const invariant = require('invariant');
 
-var {Repeat} = Immutable;
+const {Repeat} = Immutable;
 
 import type CharacterMetadata from 'CharacterMetadata';
 import type ContentState from 'ContentState';
@@ -34,18 +34,18 @@ function insertTextIntoContentState(
     '`insertText` should only be called with a collapsed range.',
   );
 
-  var len = text.length;
+  const len = text.length;
   if (!len) {
     return contentState;
   }
 
-  var blockMap = contentState.getBlockMap();
-  var key = selectionState.getStartKey();
-  var offset = selectionState.getStartOffset();
-  var block = blockMap.get(key);
-  var blockText = block.getText();
+  const blockMap = contentState.getBlockMap();
+  const key = selectionState.getStartKey();
+  const offset = selectionState.getStartOffset();
+  const block = blockMap.get(key);
+  const blockText = block.getText();
 
-  var newBlock = block.merge({
+  const newBlock = block.merge({
     text:
       blockText.slice(0, offset) +
       text +
@@ -57,7 +57,7 @@ function insertTextIntoContentState(
     ),
   });
 
-  var newOffset = offset + len;
+  const newOffset = offset + len;
 
   return contentState.merge({
     blockMap: blockMap.set(key, newBlock),
diff --git a/src/model/transaction/modifyBlockForContentState.js b/src/model/transaction/modifyBlockForContentState.js
index 2f029e8898..592324cad6 100644
--- a/src/model/transaction/modifyBlockForContentState.js
+++ b/src/model/transaction/modifyBlockForContentState.js
@@ -25,10 +25,10 @@ function modifyBlockForContentState(
   selectionState: SelectionState,
   operation: (block: BlockNodeRecord) => BlockNodeRecord,
 ): ContentState {
-  var startKey = selectionState.getStartKey();
-  var endKey = selectionState.getEndKey();
-  var blockMap = contentState.getBlockMap();
-  var newBlocks = blockMap
+  const startKey = selectionState.getStartKey();
+  const endKey = selectionState.getEndKey();
+  const blockMap = contentState.getBlockMap();
+  const newBlocks = blockMap
     .toSeq()
     .skipUntil((_, k) => k === startKey)
     .takeUntil((_, k) => k === endKey)
diff --git a/src/model/transaction/removeEntitiesAtEdges.js b/src/model/transaction/removeEntitiesAtEdges.js
index 634def68b5..61193f56bf 100644
--- a/src/model/transaction/removeEntitiesAtEdges.js
+++ b/src/model/transaction/removeEntitiesAtEdges.js
@@ -18,37 +18,37 @@ import type {EntityMap} from 'EntityMap';
 import type SelectionState from 'SelectionState';
 import type {List} from 'immutable';
 
-var CharacterMetadata = require('CharacterMetadata');
+const CharacterMetadata = require('CharacterMetadata');
 
-var findRangesImmutable = require('findRangesImmutable');
-var invariant = require('invariant');
+const findRangesImmutable = require('findRangesImmutable');
+const invariant = require('invariant');
 
 function removeEntitiesAtEdges(
   contentState: ContentState,
   selectionState: SelectionState,
 ): ContentState {
-  var blockMap = contentState.getBlockMap();
-  var entityMap = contentState.getEntityMap();
+  const blockMap = contentState.getBlockMap();
+  const entityMap = contentState.getEntityMap();
 
-  var updatedBlocks = {};
+  const updatedBlocks = {};
 
-  var startKey = selectionState.getStartKey();
-  var startOffset = selectionState.getStartOffset();
-  var startBlock = blockMap.get(startKey);
-  var updatedStart = removeForBlock(entityMap, startBlock, startOffset);
+  const startKey = selectionState.getStartKey();
+  const startOffset = selectionState.getStartOffset();
+  const startBlock = blockMap.get(startKey);
+  const updatedStart = removeForBlock(entityMap, startBlock, startOffset);
 
   if (updatedStart !== startBlock) {
     updatedBlocks[startKey] = updatedStart;
   }
 
-  var endKey = selectionState.getEndKey();
-  var endOffset = selectionState.getEndOffset();
-  var endBlock = blockMap.get(endKey);
+  const endKey = selectionState.getEndKey();
+  const endOffset = selectionState.getEndOffset();
+  let endBlock = blockMap.get(endKey);
   if (startKey === endKey) {
     endBlock = updatedStart;
   }
 
-  var updatedEnd = removeForBlock(entityMap, endBlock, endOffset);
+  const updatedEnd = removeForBlock(entityMap, endBlock, endOffset);
 
   if (updatedEnd !== endBlock) {
     updatedBlocks[endKey] = updatedEnd;
@@ -77,7 +77,7 @@ function getRemovalRange(
   start: number,
   end: number,
 } {
-  var removalRange;
+  let removalRange;
 
   // Iterates through a list looking for ranges of matching items
   // based on the 'isEqual' callback.
@@ -110,17 +110,17 @@ function removeForBlock(
   block: BlockNodeRecord,
   offset: number,
 ): BlockNodeRecord {
-  var chars = block.getCharacterList();
-  var charBefore = offset > 0 ? chars.get(offset - 1) : undefined;
-  var charAfter = offset < chars.count() ? chars.get(offset) : undefined;
-  var entityBeforeCursor = charBefore ? charBefore.getEntity() : undefined;
-  var entityAfterCursor = charAfter ? charAfter.getEntity() : undefined;
+  let chars = block.getCharacterList();
+  const charBefore = offset > 0 ? chars.get(offset - 1) : undefined;
+  const charAfter = offset < chars.count() ? chars.get(offset) : undefined;
+  const entityBeforeCursor = charBefore ? charBefore.getEntity() : undefined;
+  const entityAfterCursor = charAfter ? charAfter.getEntity() : undefined;
 
   if (entityAfterCursor && entityAfterCursor === entityBeforeCursor) {
-    var entity = entityMap.__get(entityAfterCursor);
+    const entity = entityMap.__get(entityAfterCursor);
     if (entity.getMutability() !== 'MUTABLE') {
-      var {start, end} = getRemovalRange(chars, entityAfterCursor, offset);
-      var current;
+      let {start, end} = getRemovalRange(chars, entityAfterCursor, offset);
+      let current;
       while (start < end) {
         current = chars.get(start);
         chars = chars.set(start, CharacterMetadata.applyEntity(current, null));